Active air removal system operating modes of an extracorporeal blood circuit

ABSTRACT

A disposable, integrated extracorporeal blood circuit employed during cardiopulmonary bypass surgery performs gas exchange, heat transfer, and microemboli filtering functions in a way as to conserve volume, to reduce setup and change out times, to eliminate a venous blood reservoir, and to substantially reduce blood-air interface. Blood from the patient or prime solution is routed through an air removal device that is equipped with air sensors for detection of air. An active air removal controller removes detected air from blood in the air removal device. A disposable circuit support module is used to mount the components of the disposable, integrated extracorporeal blood circuit in close proximity and in a desirable spatial relationship to optimize priming and use of the disposable, integrated extracorporeal blood circuit. A reusable circuit holder supports the disposable circuit support module in relation to a prime solution source, the active air removal controller and other components.

REFERENCE TO RELATED APPLICATIONS

This application claims benefit of Provisional No. 60/440,005 filed Jan.14, 2003, and Provisional No. 60/515,619 filed Oct. 30, 2003.

Reference is hereby made to commonly assigned co-pending U.S. patentapplication Ser. No 10/473,598 filed on even date herewith forEXTRACORPOREAL BLOOD CIRCUIT AIR REMOVEL SYSTEM AND METHOD in the namesof Robert W. Olsen, Walter L. Carpenter, John B. Dickey, Frederick A.Shorey, Laura A. Yonce, and Mark D. Stringham; Ser. No 10/743,373 filedon an even date herewith for DISPOSABLE, INTEGRATED, EXTRACORPOREALBLOOD CIRCUIT in the names of Walter L. Carpenter, Robert W. Olsen,Stefanie Heine, Frederick A. Shorey, and Laura A. Yonce; Ser. No10/743,357 filed on an even date herewith for EXTRACORPOREAL BLOODCIRCUIT PRIMING SYSTEM AND METHOD in the names of Walter L. Carpenter,Robert W. Olsen, Frederick A. Shorey, Mark G. Bearss, Bruce R. Jones,and Laura A. Yonce; and Ser. No 10/743,599 filed on an even dateherewith for ACTIVE AIR REMOVAL FROM AN EXTRACORPOREAL BLOOD CIRCUIT inthe names of Robert W. Olsen, Walter L. Carpenter, John B. Dickey, andMark D. Stringham.

1. Field of the Invention

This invention relates to extracorporeal blood circuits, systems, andmethods of use and more particularly to a disposable, integratedextracorporeal blood circuit comprising a plurality of components andlines interconnecting components supported spatially in 3-D space by acomponent organizing and supporting system, the components including anair removal device, particularly a Venous Air Removal Device (VARD),from which air is purged under the control of a reusable Active AirRemoval (AAR) controller operable in a Self-Test Mode, a Standby Mode,and an Automatic Mode.

2. Background of the Invention

Conventional cardiopulmonary bypass uses an extracorporeal blood circuitthat is to be coupled between arterial and venous cannulae and includesa venous drainage or return line, a venous blood reservoir, a bloodpump, an oxygenator, an arterial filter, and blood transporting tubingor “lines”, ports, and valves interconnecting these components. Priorart, extracorporeal blood circuits as schematically depicted in FIGS.1–3 and described in commonly assigned U.S. Pat. No. 6,302,860, drawvenous blood of a patient 10 during cardiovascular surgery through thevenous cannula (not shown) coupled to venous return line 12, oxygenatesthe blood, and returns the oxygenated blood to the patient 10 through anarterial line 14 coupled to an arterial cannula (not shown). Cardiotomyblood and surgical field debris that is aspirated by a suction device 16is pumped by cardiotomy pump 18 into a cardiotomy reservoir 20.

Air can enter the extracorporeal blood circuit from a number of sources,including around the venous cannula, through loose fittings of the linesor ports in the lines, and as a result of various unanticipatedintra-operative events. It is necessary to minimize the introduction ofair in the blood in the extracorporeal blood circuit and to remove anyair that does accumulate in the extracorporeal blood circuit before thefiltered and oxygenated blood is returned to the patient through thearterial cannula to prevent injury to the patient. Moreover, if acentrifugal blood pump is used, a large volume of air accumulating inthe venous line of the extracorporeal blood circuit can accumulate inthe blood pump and either de-prime the blood pump and deprive it of itspumping capability or be pumped into the oxygenator and de-prime theoxygenator, inhibiting oxygenation of the blood.

In practice, it is necessary to initially fill the cannulae with thepatient's blood and to prime (i.e., completely fill) the extracorporealblood circuit with a bio-compatible prime solution before the arterialline and the venous return lines are coupled to the blood filledcannulae inserted into the patient's arterial and venous systems,respectively. The volume of blood and/or prime solution liquid that ispumped into the extracorporeal blood circuit to “prime” it is referredto as the “prime volume”. Typically, the extracorporeal blood circuit isfirst flushed with CO₂ prior to priming. The priming flushes out anyextraneous CO₂ gas from the extracorporeal blood circuit prior to theintroduction of the blood. The larger the prime volume, the greater theamount of prime solution present in the extracorporeal blood circuitthat mixes with the patient's blood. The mixing of the blood and primesolution causes hemodilution that is disadvantageous and undesirablebecause the relative concentration of red blood cells must be maintainedduring the operation in order to minimize adverse effects to thepatient. It is therefore desirable to minimize the volume of primesolution that is required.

In one conventional extracorporeal blood circuit of the type depicted inFIG. 1, venous blood from venous return line 12, as well as de-foamedand filtered cardiotomy blood from cardiotomy reservoir 20, aredischarged into a venous blood reservoir 22. Air entrapped in the venousblood rises to the surface of the blood in venous blood reservoir 22 andis vented to atmosphere through a purge line 24. The purge line 24 istypically about a 6 mm ID flexible tubing, and the air space above theblood in venous blood reservoir 22 is substantial. A venous blood pump26 draws blood from the venous blood reservoir 22 and pumps it throughan oxygenator 28, an arterial blood filter 30, and the arterial line 14to return the oxygenated and filtered blood back to the patient'sarterial system via the arterial cannula coupled to the arterial line14.

A negative pressure with respect to atmosphere is imposed upon the mixedvenous and cardiotomy blood in the venous blood reservoir 22 as it isdrawn by the venous blood pump 26 from the venous blood reservoir 22.The negative pressure causes the blood to be prone to entrain airbubbles. Although arterial blood filters, e.g., arterial blood filter30, are designed to capture and remove air bubbles, they are notdesigned to handle larger volumes of air that may accumulate in theextracorporeal blood circuit. The arterial blood filter 30 is basicallya bubble trap that traps any air bubbles larger than about 20–40 micronsand discharges the air to atmosphere through a typically about 1.5 mm IDpurge line 32. The arterial filter 30 is designed to operate at positiveblood pressure provided by the venous blood pump 26. The arterial bloodfilter 30 cannot prevent accumulation of air in the venous blood pump 26and the oxygenator 28 because it is located in the extracorporeal bloodcircuit downstream from them.

As shown in FIG. 2 from the above-referenced '860 patent, it has beenproposed to substitute an assisted venous return (AVR) extracorporealblood circuit for the conventional extracorporeal blood circuit of thetype depicted in FIG. 1, whereby venous blood is drawn under negativepressure from the patient's body. The arterial blood filter 30 is movedinto the venous return line 12 upstream of the venous blood pump 26 tofunction as a venous blood filter 30′. The venous blood reservoir 22,which accounts for a major portion of the prime volume of theextracorporeal blood circuit, is thereby eliminated. De-foamed andfiltered cardiotomy blood from cardiotomy reservoir 20 is drained intothe venous blood filter 30, and venous blood in venous return line 12and the venous cannula coupled to it is pumped through the venous bloodfilter 30. Exposure of the venous blood to air is reduced because thevenous blood filter 30′ does not have an air space between its inlet andoutlet (except to the extent that air accumulates above the venous bloodinlet), as the venous blood reservoir 22 does. Suction is provided inthe venous return line 12 through the negative pressure applied at theoutlet of venous blood filter 30′ by the venous blood pump 26 to pumpthe filtered venous blood through the oxygenator 28 and into thearterial blood line 14 to deliver it back to patient 10. Again, thevenous blood filter 30′ is basically a bubble trap that traps any airbubbles larger than about 20–40 microns and discharges the air through atypically about 1.5 mm ID purge line 32.

The arterial blood filter 30 is also relocated with respect to thecardiotomy reservoir 20 and modified to function as a venous bloodfilter 30′ in the extracorporeal blood circuit shown in FIG. 3.Evacuation of air from venous blood received through venous return line12 is facilitated by increasing the size of the purge port 34 of thevenous blood filter 30′ to accept a larger diameter purge line 42, e.g.a 6 mm ID line, rather than the 1.5 mm ID line. A vacuum greater thanthat normally used for venous drainage is applied through purge line 42to the purge port 34 to actively purge air from venous blood filter 30.The cardiotomy reservoir 20 is at ambient pressure but is convenientlypurged by the same vacuum that purges air from venous blood filter 30. Avalve 36, e.g., a one-way check valve, is incorporated into the purgeport 34 or purge line 42 to prevent air or blood purged from thecardiotomy reservoir 20 from being drawn into venous blood filter 30′ bythe negative pressure in venous blood filter 30′ when the purging vacuumis not active.

As shown in FIG. 4 from the above-referenced '860 patent, venous bloodis drawn through the upper venous blood inlet 44 of venous blood filter30′, down through the filter 46 and a screen or other conventionalbubble trapping device (not shown), and out the venous blood outlet 48by the venous blood pump 26. The purge port 34 is located above thevenous blood inlet 44, and air that is separated out by the screen orother conventional bubble trapping device accumulates in the space 50above the venous blood inlet 44. An air sensor 38 is disposed adjacentthe purge port 34 that generates a sensor signal or modifies a signalparameter in the presence of air in the space 50. The sensor signal isprocessed by circuitry in a controller (not shown) that applies thevacuum to the purge line 42 to draw the accumulated air out of the space50. The vacuum is discontinued when the sensor signal indicates thatvenous blood is in the space 50. Thus, an “Active Air Removal” (AAR)system is provided to draw the accumulated air out of space 50 when, andonly when, air present in the space 50 is detected by air sensor 38 topurge the air and to prevent venous blood filling space 50 from beingaspirated out the purge line 42 by the purging vacuum. The purgingvacuum may be produced by a pump 40, or it may be produced by connectingthe purge line 42 to the vacuum outlet conventionally provided inoperating rooms.

Again, suction is provided in the venous return line 12 through thenegative pressure applied at the outlet 48 of venous blood filter 30′ bythe venous blood pump 26 to pump the filtered venous blood through theoxygenator 28 and into the arterial blood line 14 to deliver it back topatient 10. De-foamed and filtered cardiotomy blood is also pumped byvenous blood pump 26 from cardiotomy reservoir 20 through the oxygenator28 and into the arterial blood line 14 to deliver it back to patient 10.

While the AVR extracorporeal blood circuit illustrated in FIGS. 3 and 4,and particularly the use of the AAR method and system, represents asignificant improvement in extracorporeal circuits, its implementationcan be further refined and improved. A need remains for an AAR systemand method that optimizes the air sensor and its functions and thatdetects and responds to error conditions and faults that can arise overthe course of prolonged surgical use.

Moreover, the typical prior art extracorporeal blood circuit, e.g. theabove-described extracorporeal blood circuits of FIGS. 1–3, has to beassembled in the operating room from the above-described components,primed, and monitored during the surgical procedure while the patient ison bypass. This set-up of the components can be time-consuming andcumbersome and can result in missteps that have to be corrected.Therefore, a need remains for an extracorporeal blood circuit havingstandardized components and that can be set up for use usingstandardized setup procedures minimizing the risk of error.

The resulting distribution of the components and lines about theoperating table can take up considerable space and get in the way duringthe procedure as described in U.S. Pat. No. 6,071,258, for example. Theconnections that have to be made can also introduce air leaksintroducing air into the extracorporeal blood circuit. A need remainsfor a compact extracorporeal blood circuit that is optimally positionedin relation to the patient and involves making a minimal number ofconnections.

The lengths of the interconnected lines are not optimized to minimizeprime volume and attendant hemodilution and to minimize the bloodcontacting surface area. A large blood contacting surface area increasesthe incidences of embolization of blood cells and plasma traversing theextracorporeal blood circuit and complications associated with immuneresponse, e.g., as platelet depletion, complement activation, andleukocyte activation. Therefore, a need remains for a compactextracorporeal blood circuit having minimal line lengths and minimalblood contacting surface area.

Furthermore, a need remains for such a compact extracorporeal bloodcircuit with minimal blood-air interfaces causing air to be entrained inthe blood. In addition, it is desirable that the components be arrangedto take advantage of the kinetic assisted, venous drainage that isprovided by the centrifugal venous blood pump in an AVR extracorporealblood circuit employing an AAR system.

Occasionally, it becomes necessary to “change out” one or more of thecomponents of the extracorporeal blood circuit during the procedure. Forexample, it may be necessary to replace a blood pump or oxygenator. Itmay be necessary to prime and flush the newly constituted extracorporealblood circuit after replacement of the malfunctioning component. Thearrangement of lines and connectors may make this very difficult toaccomplish. A need therefore remains for a compact extracorporeal bloodcircuit that can be rapidly and easily substituted for a malfunctioningextracorporeal blood circuit and that can be rapidly primed.

Consequently, a need remains for a extracorporeal blood circuit that iscompactly arranged in the operating room, that takes advantage ofkinetic assist, and is small in volume to minimize the required primevolume and to minimize the blood contacting surface area and blood-airinterfaces. Moreover, a need remains for such an extracorporeal bloodcircuit that is simple to assemble in relation to other components, thatprovides for automatic monitoring of blood flow and other operatingparameters, that can be simply and rapidly primed, that provides fordetection and removal of air from the extracorporeal blood circuit, andthat facilitates change out of the extracorporeal blood circuit orcomponents employed with it during the procedure.

SUMMARY OF THE INVENTION

The present invention addresses at least some of these needs in uniqueand advantageous ways.

This invention relates to purging methods and systems for detecting andpurging air from the components and lines of an extracorporeal bloodcircuit, particularly, a disposable, integrated extracorporeal bloodcircuit comprising a plurality of components and lines interconnectingcomponents supported spatially in 3-D space. The purging system andmethod employ an air removal device incorporated into the extracorporealblood circuit in which air accumulates and a reusable Active Air Removal(AAR) controller interconnected with the air removal device to purge theaccumulated air therefrom.

The AAR controller is operable in a Self-Test Mode, a Standby Mode, andan Automatic Mode. Air is automatically or manually drawn air from bloodor prime solution circulating through the disposable, integratedextracorporeal blood circuit and accumulating in the air removal device.In such modes, various sensor output signals are examined to determineany error conditions or declared error states of the purging systemcomprising the AAR controller and the air removal device as well asother ambient conditions, e.g., absence of mains power and sufficientvacuum to draw air from the air removal device. The AAR controllergenerates displays of operating state and error messages and emitsaudible and visible Cautions and Alarms in response to detected errorconditions.

In preferred embodiments, the air removal device comprises a housingenclosing a chamber, an air removal device purge port through thehousing to the chamber, and an air sensor supported by the air removaldevice housing. The air sensor generates an air sensor signal indicativeof the absence or presence of air in the air removal device housing. Anair removal device purge line is coupled to the air removal device purgeport, the air removal device purge line extending to a purge lineconnector adapted to be coupled to a vacuum source to apply suction tothe air removal device purge port to draw air therefrom.

A portion of the air removal purge line extends through a purge valve ofthe AAR controller. The purge valve is movable between a purge valveopen position and a purge valve closed position. The purge valve isopened in response to an air sensor signal indicative of the presence ofair in the air removal device chamber to allow air sensed in the airremoval device to be purged through the purge line by the suction of thevacuum source. The AAR controller removes air accumulating in the airremoval device chamber until fluid is sensed in the air removal purgeline by a fluid in line (FIL) sensor. Automatic air removal isinhibited, that is interrupted if already started or prevented if notstarted, by closure of the pinch valve if an error condition of thepurging system is detected. Mechanical opening of the purge valve isenabled at any time.

In a preferred embodiment, the VARD is equipped with upper and lower airsensors for providing sensor signals when air accumulates in the VARDand needs to be removed through a VARD air removal purge line coupled toa VARD purge port.

This summary of the invention has been presented here simply to pointout some of the ways that the invention overcomes difficulties presentedin the prior art and to distinguish the invention from the prior art andis not intended to operate in any manner as a limitation on theinterpretation of claims that are presented initially in the patentapplication and that are ultimately granted.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other advantages and features of the present invention will bemore readily understood from the following detailed description of thepreferred embodiments thereof, when considered in conjunction with thedrawings, in which like reference numerals indicate identical structuresthroughout the several views, and wherein:

FIG. 1 is a schematic diagram of a first prior art extracorporeal bloodcircuit that uses a venous reservoir;

FIG. 2 is a schematic diagram of a second prior art extracorporeal bloodcircuit that does not use a venous reservoir;

FIG. 3 is a schematic diagram of a third prior art extracorporeal bloodcircuit that does not use a venous reservoir and employs a venous bloodfilter with active air removal;

FIG. 4 is a simplified schematic view of the prior art venous bloodfilter of FIG. 3;

FIG. 5 is a schematic view of the components of the disposable,integrated extracorporeal blood circuit of the present invention inrelation to prime solution holding bags and a sequestering bag;

FIG. 6 is a representational diagram of the arrangement of the principlecomponents of the disposable, integrated extracorporeal blood circuit ofFIG. 5 supported in 3-D space by a disposable circuit support modulethat is mounted to a reusable circuit holder that supports furtherreusable components and is adapted to be mounted to the a heart lungmachine console for operating the oxygenator and blood pump of thedisposable, integrated extracorporeal blood circuit;

FIG. 7 is a perspective view of the disposable circuit support module ofFIG. 6;

FIG. 8 is a schematic view of the components of the disposable,integrated extracorporeal blood circuit of the present inventionsupported by the disposable circuit support module of FIGS. 6 and 7;

FIGS. 9–11 are schematic views of the components of the disposable,integrated extracorporeal blood circuit of the present invention inrelation to a sequestering bag and first and second prime solution bagsillustrating the steps of priming the disposable, integratedextracorporeal blood circuit with prime solution;

FIGS. 12A and 12B are cross-section views of one embodiment of a VARDemployed in the disposable, integrated extracorporeal blood circuit inaccordance with the present invention;

FIG. 13A is a schematic view of the orientation of piezoelectricelements employed in the VARD illustrated in FIGS. 12A and 12B inaccordance with the present invention;

FIG. 13B is a plan view of a piezoelectric element employed in the VARDillustrated in FIGS. 12A and 12B;

FIG. 13C is a side cross-section view taken along lines 13C—13C in FIG.13B of the internal components of the piezoelectric element;

FIG. 13D is a partial exploded perspective view of the VARD andpiezoelectric elements;

FIG. 13E is a further partial exploded perspective view of the VARD andpiezoelectric elements;

FIG. 14 is a plan view of an AAR controller employed in the practice ofthe present invention;

FIG. 15 is a system block diagram of the AAR controller of FIG. 14;

FIGS. 16A and 16B are a high level flow chart illustrating the SelfTest, Standby, and Automatic Modes of operation of the AAR system of thepresent invention;

FIGS. 17A and 17B are a high level flow chart illustrating the steps ofoperation of the AAR system in the Automatic Mode;

FIG. 18 is an LCD screen display during the Self-Test Mode;

FIG. 19 is an LCD screen display during the Standby Mode;

FIGS. 20–26 are LCD screen displays responsive to depression of certainkeys by the perfusionist during the Standby Mode;

FIGS. 27 and 28 are LCD screen displays indicating the status of thepurge valve during the Automatic Mode;

FIG. 29 is an LCD screen display instructing the perfusionist tomechanically open the pinch valve due to operation of the AAR controllerin the battery backup state;

FIGS. 30–36 are LCD screen displays indicating error and system powerstates during the Self-Test Mode;

FIGS. 37–42 are LCD screen displays indicating error and system powerstates during the Standby Mode; and

FIGS. 43–57 are LCD screen displays indicating error and system powerstates during the Automatic Mode.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The various aspects of the present invention are preferably embodied ina method and system that incorporates a disposable, integratedextracorporeal blood circuit with reusable components including thereusable components of a heart-lung machine. The disposable, integratedextracorporeal blood circuit preferably comprises the set of principalcomponents comprising a VARD, a centrifugal blood pump, an oxygenator,and an arterial blood filter all interconnected with fluid lines. Thedisposable centrifugal blood pump is coupled with the reusable bloodpump driver that is in turn coupled to a pump driver console. An oxygenline is coupled to the disposable blood oxygenator via a flow meter andblender. Water lines are coupled to the disposable blood oxygenator viaa module for controlling water flow and water temperature. The preferredembodiment of the VARD of the present invention comprises a venousfilter that provides an AAR function under the control of a reusable AARcontroller. The disposable, integrated extracorporeal blood circuit ofthe preferred embodiment of the present invention further comprises adisposable component organizing device or circuit support module forsupporting the principal components and lines in a predetermined 3-Dspatial relationship. The preferred embodiment of the present inventionfurther comprises a reusable circuit holder adapted to be coupled to thereusable components of the heart lung machine to support the AARcontroller and the reusable circuit support module.

The disposable, integrated extracorporeal blood circuit of the presentinvention preferably has access ports through which the operator orperfusionist may administer medications, fluids, and blood. In addition,the extracorporeal blood circuit preferably includes multiple sites forsampling blood and for monitoring various parameters, e.g., temperature,pressure, and blood gas saturation. Clamps and valves are also disposedin the lines extending between or from the principal components of thedisposable, integrated extracorporeal blood circuit. The disposable,integrated extracorporeal blood circuit of the present invention can beset up and changed out more rapidly than conventional extracorporealblood circuits, and arrangement of the supplied components minimizes thepossibility of erroneous setup. The disposable, integratedextracorporeal blood circuit of the present invention is a closed systemthat reduces the air-blood interface and that minimizes the bloodcontacting surface area.

The disposable, integrated extracorporeal blood circuit of the presentinvention may be rapidly primed with prime solution. During priming, thevenous return line connector is coupled to the arterial line connector.The extracorporeal blood circuit is supported in 3-D space so that thecomponents and lines interconnecting the components are disposed betweena circuit high elevation and a circuit low elevation. A prime solutionsource is supported at a source elevation higher than the circuit highelevation, and prime solution is delivered into the integratedextracorporeal blood circuit at the circuit low elevation. The flow ofprime solution from the prime solution source into the extracorporealblood circuit is controlled to upward fill the components and lines ofthe extracorporeal blood circuit with prime solution, thereby displacingair upward. Air is purged from the extracorporeal blood circuit as theprime solution fills the extracorporeal blood circuit.

The preferred embodiment of the best mode of practicing the inventiondisclosed herein incorporates all of the features of the presentinvention. However, it will be understood that the various aspects ofthe present invention can be practiced in alternative contexts than thecontext provided by the described preferred embodiment.

Disposable, Integrated Extracorporeal Blood Circuit

The components of the disposable, integrated extracorporeal bloodcircuit 100 are illustrated in FIGS. 5 and 6. The principal componentsof the disposable, integrated extracorporeal circuit 100 comprise theVARD 130, the centrifugal blood pump 150, the oxygenator 160, and thearterial blood filter 180. The disposable, integrated extracorporealblood circuit 100 is illustrated in FIG. 5 in relation to prime solutionholding bags 380 and 390 that drain prime solution into the disposable,integrated extracorporeal blood circuit 100 during priming and asequestering bag 370 adapted to sequester excess prime solution or bloodat times during the bypass procedure. The prime solution holding bags380 and 390 are conventional IV bags that have penetrable seals thatspikes can be inserted through in use. The sequestering bag 370 issupplied with three bag tubes 372, 374 and 376 that have respectiveRoberts clamps 382, 384 and 386 applied thereto to selectively clampshut or open the bag tube lumens. For example, the Roberts clamps 382,384, and 386 may be clamped shut when the sequestering bag 370 isattached to or detached from the disposable, integrated extracorporealblood circuit 100. The interconnection of these principal components andthe prime solution holding bags 380 and 390 and sequestering bag 370through lines and further components is first described as follows.

The disposable, integrated extracorporeal blood circuit 100 is alsoillustrated in FIG. 5 with a U-shaped, tubular, pre-bypass loop 120 thatcan be selectively used to connect the arterial blood line 114 with thevenous return line 112 during flushing of the disposable, integratedextracorporeal blood circuit 100 with CO₂ gas and during priming of thedisposable, integrated extracorporeal blood circuit 100 with primesolution from prime solution bags 380 and 390 as described further belowwith respect to FIGS. 9–11. The pre-bypass loop 120 is coupled to thevenous return line 112 by a quick connect connector 102 and to thearterial line 114 by a quick connect connector 104. The arterial line114 and venous return line 112 are preferably formed of 0.375 inch IDPVC tubing.

It will be understood that the pre-bypass loop 120 is disconnected fromthe venous and arterial blood lines 112 and 114, respectively, after thedisposable, integrated extracorporeal blood circuit 100 is primed. Tablelines extending to venous and arterial cannulae extending into thepatient are then connected to the respective venous return line 112 andarterial line 114 through quick connectors 102 and 104, respectively.Any air that enters the venous return line 112 during this switchingprocess is eliminated by the AAR system and method of the presentinvention as described further below.

The venous return line 112 extends from the quick connector 102 througha quick disconnect connector 122 to the inlet 132 of the VARD 130. Theassembly of a tri-optic measurement cell (TMC) 38 BioTrend® connector108 having a 0.375 inch ID lumen coupled to a utility connector 110having a 0.375 inch ID lumen is interposed in the venous return line112. The TMC 38 BioTrend® connector 108 may be used to hold a TMC cell(not shown) of the BioTrend™ Oxygen Saturation and Hematocrit System,sold by Medtronic, Inc., to measure blood oxygen saturation and bloodhematocrit of venous blood passing through the venous return line 112.The utility connector 110 supports a plurality of standard luer portsand barbed ports.

A venous blood sampling line 106, preferably formed of 0.125 inch ID PVCtubing, extends between one port of the utility connector 110 to oneside of a manifold 115. The manifold 115 comprises a rigid tube having a0.125 inch ID tube lumen and three stopcocks with side vent portsarrayed along the tube and employed as described further below.

A venous blood pressure monitoring line 116 that is preferably formed of0.125 inch ID PVC tubing is coupled to a stopcock 196 attached to a luerport of the utility connector 110 and extends to a pressure isolator 117and stopcock 125. The pressure isolator 117 of the venous blood pressuremonitoring line 116 has a flexible bladder and is sized to be attachedto a Medtronic® Model 6600 pressure monitor and display box. Venousblood pressure monitoring may be used to optimize kinetic drainage. Forexample, venous blood pressure that is too high, too low, oscillatingand/or chattering may indicate that the speed of the venous blood pumpis incorrect and should be adjusted.

An arterial filter recirculation line 118, preferably formed of 0.125inch ID PVC tubing and including a check valve 119, extends from afurther luer port of the utility connector 110 to the arterial filterpurge port 186 of the arterial filter 180. Under operating conditionsdescribed below, a small volume of arterial blood and any air bubblesare drawn through the arterial filter recirculation line 118 and checkvalve 119 from the arterial filter 180 into the venous return line 112.The check valve 119 prevents reverse flow of venous blood into thearterial filter 180.

In certain cases, it is desirable to provide passive venting of thevenous blood in the venous return line 112, and so a short, 0.250 inchID, tube stub 124, terminating in a 0.250 inch ID barbed port, extendsfrom the utility connector 110 to function as a vent blood return port.A Roberts clamp 194 is fitted across the 0.250 inch ID tube stub 124 tobe opened or closed in use when the tube stub is coupled to active orpassive venting equipment, e.g., the Gentle Vent passive venting systemsold by Medtronic, Inc.

A blood temperature monitoring adaptor 126 is provided extending fromthe utility connector 110 and enabling insertion of a temperature probeconnected with temperature monitoring equipment.

The VARD 130 is described further below with reference to FIGS. 12A, 12Band 13. In general, air that is entrained in the venous blood drawnthrough the VARD inlet 132 tends to be separated from the venous bloodwithin VARD 130 and accumulates in an upper chamber thereof. Thepresence of air is detected by signals output from air sensors locatedabout the VARD 130, and the air is evacuated from the chamber.

The venous blood outlet 136 of VARD 130 is coupled to one branch of a“Y” style segment or blood pump inlet line 156, preferably formed of0.375 inch ID PVC. The trunk of the “Y” style segment or line 156 iscoupled to the blood pump inlet 152 of the centrifugal venous blood pump150. The blood pump 150 is adapted to be positioned in use with a drivemotor (not shown) as described further below that is selectivelyoperated to draw venous blood through the VARD 130 and pump it into theoxygenator 160.

Preferably, venous blood pump 150 is a centrifugal blood pump, e.g., aBio-Pump® centrifugal blood pump sold by Medtronic, Inc., that iscapable of providing sufficient negative pressure (to −200 mm Hg) forkinetic assisted drainage of venous blood from the patient. Operation ofthe Bio-Pump® centrifugal blood pump is controlled by a Bio-Console®drive console sold by Medtronic, Inc. The Bio-Console® drive consoleprovides electrical energy to drive a reusable pump drive that in turndrives the Bio-Pump® centrifugal blood pump. Exemplary blood pump drivesystems are disclosed, for example, in U.S. Pat. Nos. 5,021,048 and5,147,186.

A fluid infusion line 176, preferably formed of 0.375 inch ID PVCtubing, is coupled to the other branch of the “Y” style segment or line156 and extends to a connection with the tube 376 of the sequesteringbag 370 made through a tubing size adaptor and Roberts clamp 197. Primesolution can be selectively pumped or drained from the sequestering bag370 during priming, and blood can be selectively pumped or drained fromthe sequestering bag 370 during the course of the bypass procedure.

The location of VARD 130 upstream of venous blood pump 150 in thedepicted closed system provides kinetic assisted venous drainage due tothe negative pressure exerted on venous blood by the venous blood pump150. An AAR system and method automatically detects and suctions off airthat collects in a high, quiescent point in the venous line of thedisposable, integrated extracorporeal blood circuit 100. In thepreferred embodiment of the present invention, the high point is withinthe upper part of VARD 130 adjacent to the purge port 134.

A VARD purge line 141, preferably formed of 0.250 inch ID PVC tubing, iscoupled to the purge port 134 of VARD 130 through a stopcock 135 andextends to a purge line distal end connector 143 adapted to be coupledto a vacuum line. A VARD purge line segment 147 formed of siliconerubber and a vacuum sensor line 145 are coupled to an AAR controller asdescribed further below. VARD purge line 141 or the purge port 134 ofVARD 130 may include a means, e.g., a one-way check valve, to preventair from being pulled into the VARD 130 prior to attachment of the purgeline distal end connector 143 to the vacuum line. For example, a checkvalve 123 is located at the connection of the VARD purge line 141 withthe VARD purge line segment 147. In addition, an air permeable,hydrophobic, fluid isolation filter 149, is located in a T-shaped branchof the purge line distal end connector 143 to prevent any bloodsuctioned from VARD 130 during operation of the AAR system from beingsuctioned into the vacuum sensor within the AAR controller that thevacuum sensor line 145 is connected to. The fluid isolation filter 149is preformed with a female luer lock and a male luer lock for attachmentbetween the T-connector of VARD purge line segment 147 and the vacuumsensor line 145, e.g., a 25 mm filter enclosing 0.2 μm Versapor® 200Rhydrophobic acrylic copolymer on a non-woven support available from PALLLife Sciences Division, Ann Arbor, Mich., of Pall Corporation.

A purging vacuum produced by a pump or a vacuum outlet conventionallyprovided in operating rooms is applied through a vacuum line coupled tothe purging line distal end connector 143. Although not shown in FIG. 5,a collection container or trap is to be interposed between purge linedistal end connector 143 and the vacuum source or pump to trap the redblood cells that may be suctioned from VARD 130 through VARD purge line141 for possible salvage and return to the patient. The liquid trap canbe a standard hard-shell venous reservoir, a standard cardiotomyreservoir, a chest drainage container, or a blood collection reservoirused with the autoLog™ Autotransfusion System sold by Medtronic, Inc.The blood collection reservoir used with the autoLog™ AutotransfusionSystem has a 40 micron filter and may be mounted onto a mast of theconsole of the heart-lung machine or other equipment in the operatingroom to function as a liquid trap. Preferably, the vacuum source or pumpis capable of supplying a minimum of about −215 mmHg vacuum, andpreferably is capable of suctioning about 400 ml/min of air from theliquid trap without the vacuum decreasing below about −180 mmHg.

The blood pump outlet 154 is coupled to one end of a “T” style connectorfunctioning as an oxygenator inlet line 158, preferably formed of 0.375inch ID PVC tubing. The other end of the “T” style line 158 is coupledto the oxygenator blood inlet 170 of oxygenator 160. The oxygenatorblood inlet 170 and the venous blood outlet 154 are thereby coupledtogether and supported at substantially the same venous bloodoutlet/inlet elevation by the “T” style line 158.

One end of a priming line 159, preferably formed of 0.250 inch ID PVCtubing, is coupled to a side branch of the “T” style connector or line158. The priming line 159 extends to branching segments or lines 151 and153, preferably formed of 0.250 inch ID PVC tubing, that terminate inspikes that are inserted into the penetrable openings or seals of theprime solution bags 380 and 390. Roberts clamps 161, 163, and 165 arefitted over the respective tubing segments or lines 151, 153 and 159 toselectively clamp shut or open the tube lumens during gravity priming ofthe disposable, integrated extracorporeal blood circuit 100 as describedfurther below. The side branch of the “T” style line 158 preferablyextends away from the blood pump 150 at an angle less than 90° to thetrunk of the “T” style line 158 so that any air that is entrained in theprime solution does not stick at the junction of the side branch andinstead rises through the side branch and the priming line 159 toaccumulate in a prime solution bag 380 or 390. Due to this arrangement,no air bubbles are entrapped in the line 159 during priming or operationof the disposable, integrated extracorporeal blood circuit 100.

A blend of oxygen and air enters the oxygenator 160 through gas inlet162 and exits the oxygenator 160 through access port 164. Gas exchangebetween the oxygen and the venous blood entering oxygenator blood inlet170 then takes place by diffusion through the pores in the hollow fibersof the oxygenator 160. Thermal energy may be added or removed throughthe blood heat exchanger that is integral with the oxygenator 160. Wateris heated or cooled by a heater/cooler of the heart-lung machine andwarmed or chilled water is delivered to the water-side of the heatexchanger. Water enters the heat exchanger through a hose (not shown)coupled to water inlet port 166 and exits the heat exchanger throughwater outlet port 168 and a hose (not shown) coupled thereto. Theoxygenator 160 is preferably a blood oxygenator of the type disclosedU.S. Pat. Nos. 4,975,247 5,312,589, 5,346,621, 5,376,334, 5,395,468,5,462,619, and 6,117,390, for example. Preferably, oxygenator 160comprises an AFFINITY® hollow fiber membrane oxygenator sold byMedtronic, Inc.

The temperature modulated, oxygenated blood is pumped out of theoxygenator blood outlet 169 and through an oxygenator outlet line 188,preferably formed of 0.375 inch ID PVC tubing, that is coupled to thearterial filter inlet 182 of the arterial filter 180. The heated orcooled oxygenated blood can also be pumped out of a branch of theoxygenator outlet 169 and through an arterial blood sampling line 172,preferably formed of 0.125 inch ID PVC tubing and including a checkvalve 121, that extends to one input of manifold 115 for sampling ofarterial blood and for drug administration.

A temperature monitoring adaptor 171 similar to adaptor 126 branchesfrom of the oxygenator blood outlet 169 to be used to monitor oxygenatedblood temperature.

A recirculation/cardioplegia line 174, preferably formed of 0.250 inchID PVC tubing, extends from a recirculation port 173 of the oxygenator160 to a “Y” style connector having two branches 175 and 177. The branch175 is coupled to the luer port of line 58 of the sequestering bag 370.A Roberts clamp 195 is used to open or close the branch 175 of the “Y”style connector coupled to line 58 so that prime solution or oxygenatedblood can be selectively pumped into the sequestering bag 370 during thecourse of priming or performance of the bypass procedure. A secondbranch 177 of the recirculation/cardioplegia line 174 comprises a tubethat is provided with a closed end and can be left intact or cut away sothat the recirculation/cardioplegia line 174 can be selectively coupledto a cardiaplegia source or a hemoconcentrator while the Roberts clamp195 is closed.

The delivery of cardioplegia solution reduces or discontinues thebeating of the heart in a manner that will minimize damage to themyocardium. Cardioplegia solution can also supply other ingredients toprovide for myocardium protection and may be delivered alone or mayinclude oxygenated blood diverted from the arterial line. A cardioplegiacircuit is formed that comprises the oxygenated blood line, acardioplegia solution bag and line, a cardioplegia delivery line, a pump(e.g., peristaltic), and may also comprise pressure transducers tomonitor the solution pressure, an air detector and filters to preventbubbles from entering the heart, a timer, temperature sensors and a heatexchanger to monitor and control fluid temperature, and a device forcontrolling and recording the total volume of cardioplegia solution thatis pumped. The cardioplegia solution is delivered to the coronaryarterial network or coronary sinus for distribution throughout themyocardium and the circulatory system in a manner well known in the art.

The arterial blood filter 180 may take the form disclosed in U.S. Pat.Nos. 5,651,765 and 5,782,791, for example, and preferably comprises anAFFINITY® Arterial Filter sold by Medtronic, Inc. The oxygenated bloodis pumped under the pressure exerted by the venous blood pump 150through the arterial filter inlet 182, through a filter and screendisposed within the arterial blood filter 180, and through the arterialfilter outlet 184 into the arterial line 114. Microemboli are filteredfrom the oxygenated blood as it passes through the arterial filter 180.Air that is entrained in the oxygenated blood tends to be separated fromthe oxygenated venous blood by the screen and accumulates in an upperchamber the arterial filter 180 below arterial filter purge port 186.

The arterial filter purge port 186 is coupled to a three-way stopcock187 in the arterial filter purge port 186 that has a branch coupled toan end of arterial filter recirculation line 118. The three-way stopcock187 is normally in an air evacuation position that connects the arterialfilter recirculation line 118 with the arterial filter purge port 186. Alow volume of arterial blood and any air that collects in the upperchamber the arterial filter 180 below arterial filter purge port 186 aredrawn by blood pump 150 through the utility connector 110 and venousreturn line 112 into the VARD 130. The difference in pressure betweenthe positive pressure of the oxygenated blood within the chamber of thearterial filter 180 and the negative pressure in the venous return line112 draws the blood and air from the chamber of the arterial filter 180when the venous blood pump 150 is running and the three-way stopcock 187is moved to the air evacuation position. The check valve 119 in thearterial filter recirculation line 118 prevents reverse flow of venousblood through the recirculation line 118 when the blood pump 150 is notpumping. The three-way stopcock 187 can be manually moved to a primingposition opening the arterial filter chamber to atmosphere to facilitatepriming of the disposable, integrated extracorporeal blood circuit 100.As described below, the arterial filter 180 is fitted into a receptacleof a disposable circuit support module such that the operator canmanually lift and invert the arterial filter 180 during priming orduring the bypass procedure to facilitate evacuation of any air observedin the arterial filter 180.

The filtered, oxygenated blood is returned to the patient as arterialblood through the arterial line 114 coupled to the arterial filteroutlet 184 and through a table line fitted to the quick connector 104and coupled to an arterial canulla (not shown) or directly to an end ofan elongated arterial cannula extending into the patient's heart. Thearterial line 114 passes through a blood flow transducer connector 190that receives and supports a Bio-Probe® blood flow transducer sold byMedtronic, Inc. to make arterial flow rate measurements. In normaloperation, the Bio-Console® drive console determines arterial blood flowrate from the output signal of the Bio-Probe® flow probe transducermounted to blood flow transducer connector 190 to make flow ratemeasurements of blood flow in arterial line 114 or in oxygenator outletline 188. Oxygenated, arterial blood flow rate is generally determinedto an accuracy of +/−5%.

The above-described barbed connections and luer connections with linesor tubing preferably do not leak at pressures ranging between +750 mmHgand −300 mmHg. In addition, the barbed connections preferably withstandpull forces up to 10 lbs linear pull.

All surfaces of the disposable, integrated extracorporeal blood circuitexposed to blood should be blood compatible through the use ofbiocompatible materials e.g., silicone rubber, PVC, polycarbonate orplastisol materials. Preferably, the blood contacting surfaces of thedisposable, integrated extracorporeal blood circuit are coated withCarmeda® BioActive Surface (CBAS™) heparin coating under license fromCarmeda AB and described in U.S. Pat. No. 6,559,132, for example.

The disposable, integrated extracorporeal blood circuit 100 of thepresent invention preferably has operable flow rates of 1–6 liters perminute of blood through it without producing gas bubbles within venousblood pump 150 or through fibers of oxygenator 160. The disposable,integrated extracorporeal blood circuit is spatially arranged andsupported in 3-D space by a component organizing and supporting systemof the present invention at the height of the patient so that therespective venous return and arterial lines 112 and 114 can be made asshortened to reduce prime volume.

The above-described components of the disposable, integratedextracorporeal blood circuit 100 are spatially arranged and supported in3-D space as shown in FIG. 5 by a disposable circuit support module 200and a reusable circuit holder 300 as shown in FIGS. 6–8. Most of theabove-described lines and other components interconnecting or extendingfrom the VARD 130, the centrifugal blood pump 150, the oxygenator 160,and the arterial blood filter 180 are not shown in FIG. 6 to simplifythe illustration.

The disposable circuit support module 200 is formed of a rigid plasticmaterial having a C-shaped arm 202 extending between lower snap fittings204 and 206 and an upper snap fitting 208. A receptacle 210 is adaptedto fit onto the receiver 344 of the circuit holder 300. As shown in FIG.6, the VARD 130 and the oxygenator 160 are directly supported by theC-shaped arm 202, and the “Y” style line 156 and “T” style line 158couple the centrifugal blood pump 150 between the venous blood outlet136 and the venous blood inlet 170, whereby the blood pump 150 isindirectly supported by the C-shaped arm 202. The “Y” style line 156 and“T” style line 158 are flexible, which advantageously allows theperfusionist to grasp the blood pump 150 while it is not being drivenduring priming and tilt it to see if any air is accumulating in theblood pump chamber. Any air accumulating in the blood pump chamberduring priming, as described further below, can be dislodged in thisway.

The snap fittings 204 and 206 each comprise a fixed, concave, bandformed as part of C-shaped arm 202 and a separate U-shaped, band. Thesnap fitting 208 comprises a concave band that can be attached to ordetached from the C-shaped arm 202 and a separate U-shaped band. Theseparate U-shaped bands can be snapped into engagement with the concavebands to form a generally cylindrical retainer band dimensioned toengage the sidewalls of the oxygenator 160, the VARD 130 and thearterial blood filter 180.

During assembly, the oxygenator 160 is applied against the fixed,concave, half-band, and the U-shaped, half-band is snapped around theoxygenator 160 and to slots on either side of the fixed, concave,half-band to entrap oxygenator 160 in lower oxygenator snap fitting 204during assembly of the extracorporeal blood circuit 100 so that it isdifficult to remove the oxygenator 160. Similarly, the VARD 130 and thearterial blood filter 180 are supported and entrapped in lower and upperVARD and arterial filter snap fittings 206 and 208, respectively.

The upper snap fitting 208 encircling arterial blood filter 180 isdetachable at a clip 218 from the C-shaped arm 202. The arterial bloodfilter 180 and upper snap fitting 208 can be manually detached at clip218 and inverted by the perfusionist during priming. Any air bubblestrapped in the lower portion of the arterial blood filter 180 adjacentthe arterial filter outlet 184 can then rise up through the invertedarterial filter outlet 184 into the arterial line 114 to be drawnthrough the bypass circuit 120 and the venous return line 112 into theVARD 130 to be purged therefrom. The perfusionist can observe themovement of the air bubbles and then insert the arterial filter 180 backinto clip 218.

As shown in FIG. 8, lateral raceways 220 and vertical raceways 222 areprovided in the C-shaped arm 202 that laterally and vertically extendinglines can be fitted into. The VARD purge line 141 and the fluid infusionline 176 are extended vertically from the VARD 130 and the branch of the“Y” style line 156, respectively, through one vertical raceway 222. Thepriming line 159 and the recirculation/cardioplegia line 174 areextended laterally through the lateral raceways 220.

Disposable circuit support module 200 advantageously maintains properorientation and positioning of the supported principal components andthe lines extending between or from them to optimize function. The shortlines minimize surface area contacted by blood. The oxygenator 160 issupported by disposable circuit support module 200 so that the bloodpump outlet 154 and the oxygenator blood inlet 170 connected by “T”style connector or line 158 are at about the same circuit low elevationlevel below prime solution holding bags 380 and 390 in order tofacilitate gravity priming through priming line 159 and upward fillingof the blood pump 150 and oxygenator 160 and other circuit componentsand lines with prime solution. Disposable circuit support module 200positions the VARD 130 above the blood pump 150 and the arterial bloodfilter 180 above the VARD 130 in order to facilitate upward priming andmovement of air into the arterial filter purge port 186 to be drawn intothe VARD 130 and purged as described further below.

Module 200 is advantageously configured to allow access for clamping orunclamping the lines or tubing segments or for making connections to thevarious ports. The disposable circuit support module 200 advantageouslyallows venous blood pump 150 to be independently manipulated, e.g.,rotated, swiveled, and/or pivoted, with respect to the disposablecircuit support module 200 and holder 300. Disposable circuit supportmodule 200 maintains proper positioning/alignment of the components andlines of the disposable, integrated extracorporeal blood circuit 100 tooptimize priming of the disposable, integrated extracorporeal bloodcircuit 100 in a very short time. Preferably, disposable circuit supportmodule 200 is transparent to allow sight confirmation of prime solutionor blood in the lines and other transparent components.

Moreover, the disposable, integrated extracorporeal system 100 mountedto the disposable circuit support module 200 can be assembled as a unitand then attached to the circuit holder 300 for priming and use during abypass procedure. A replacement assembly of a disposable, integratedextracorporeal system 100 mounted to a disposable circuit support module200 as shown in FIG. 8 can be quickly assembled and substituted in achange-out during priming or the bypass procedure if it is necessary todo so.

The circuit holder 300 comprises a mast 302 that extends through a shaftcollar 304 of a mast arm assembly 306. The shaft collar 304 can be movedalong the mast 302, and mast arm assembly 306 can be fixed at a selectedposition by tightening a lever 308. The mast arm assembly 306 includes aU-shaped notch 310 that can be inserted around an upright mast (notshown) of a heart-lung machine console (not shown), and a clamp 312 canbe rotated and tightened to hold the mast 302 in a vertical orientationclose to the heart-lung machine console. The mast 302 is provided withan IV hanger 360 that the prime solution holding bags 380 and 390 andthe sequestering bag 370 can be hung from.

The mast 302 extends downward from the mast arm assembly 306 and througha collar 316 of an electronics arm assembly 314 that can be moved alongthe mast 302 and fixed in place by tightening a lever 318. Theelectronics arm assembly 314 extends to a cross-bar 326 supporting aright support arm 320 adapted to support an AAR controller and a leftsupport arm 322 adapted to support a pressure monitor and display box,e.g., the Medtronic® Model 6600 pressure monitor and display box sold byMedtronic, Inc. The angle of the cross-bar 326 with respect to theelectronics arm assembly 314 and the support angle of the right and leftsupport arms 320 and 322 with respect to the cross-bar 326 can beadjusted by loosening the lever 324, rotating the cross-bar 326 andpivoting the right and left support arms 320 and 322 to the desiredangles, and tightening the lever 324.

The lower end of the mast 302 is coupled to a laterally extendingsupport arm assembly 330 that is formed with a cable supporting androuting channel 332. A laterally extending module arm assembly 340 and adownwardly extending external drive arm assembly 350 are mounted to anupward extension 334 of the support arm assembly 330 by a spring lockmechanism 342. A tapered male receiver 344 extends upward to be receivedin the downwardly extending female receptacle 210 of the circuit supportmodule 200 when the disposable, integrated extracorporeal blood circuit100 is mounted to the circuit holder 300. Line receiving slots 348 areprovided in the laterally extending module arm assembly 340 forsupporting cables for temperature monitoring and the VARD cable 450.VARD cable 450 has a cable connector 452 that is attached to a VARDsensor connector 454 as schematically illustrated in FIG. 12B.

A TMC clip 346 is fitted to the free end of the laterally extendingmodule arm assembly 340 for engaging the TMC 38 BioTrend® connector 108into which the TMC cell of the BioTrend™ Oxygen Saturation andHematocrit System is inserted to measure venous blood oxygen saturationand venous blood hematocrit of venous blood flowing through the venousreturn line 112 of the disposable, integrated extracorporeal bloodcircuit 100. A cable (not shown) from the TMC cell supported by TMC clip346 extends to a BioTrend™ Oxygen Saturation and Hematocrit System.

The Bio-Probe® blood flow transducer sold by Medtronic, Inc. to makeblood flow rate measurements through the arterial line is adapted to bemounted to the laterally extending module arm assembly 340 at pin 354. Acable (not shown) extends from the Bio-Probe® blood flow transducersupported at pin 354 extends to a Bio-Probe® blood flow monitor sold byMedtronic, Inc.

An external drive motor for the blood pump 150 is attached to the freeend mount 352 of the external drive arm assembly 350 to mechanicallysupport and drive the blood pump 150 through magnetic coupling of amotor driven magnet in the external drive motor with a magnet of thecentrifugal blood pump 150. An adaptor can be attached to the free endmount for coupling a hand-cranked magnet with the magnet of thecentrifugal blood pump 150 in an emergency situation.

Thus, the VARD 130, the centrifugal blood pump 150, the oxygenator 160,and the arterial blood filter 180 principal components, as well as thelines and other associated components identified in FIG. 5, arespatially arranged and supported in 3-D space by the disposable circuitsupport module 200 and the reusable circuit holder 300 as shown in FIGS.6–8. The assembly is closely positioned to the heart-lung machineconsole that operates the drive motor of the centrifugal blood pump 150,supplies oxygen to the oxygenator 130, and controls the temperature ofthe blood or cardioplegia solution traversing the oxygenator 130. Theposition of the mast arm assembly 306 along the mast 302 can be adjustedto optimally extend the module arm assembly 340 toward and over thepatient during the procedure. The position of the electronics armassembly 314 along the mast 302 can be adjusted and fixed in place bytightening a lever 318 to optimally position the AAR controller andMedtronic® Model 6600 pressure monitor and display box for use duringthe bypass procedure. The fixed distance between the support armassembly 330 and the IV hanger 360 ensures that the lengths of thepriming line 159 and the fluid infusion line 176 coupled with the primesolution holding bags 380 and 390 and the sequestering bag 370,respectively, are advantageously minimized and are not affected by thepositioning of the mast arm assembly 306 along the mast 302.

Connections of the sensors, lines, ports, etc., with further componentscan be readily effected after the disposable, integrated extracorporealblood circuit 100 is assembled with the disposable circuit supportmodule 200 and mounted to the reusable circuit holder 300. For example,the reusable VARD sensor cable 450 depicted in FIG. 8 extends from theVARD connector 454 laterally through channel 332 to make a connectionwith an AAR controller in a manner described further herein.

In accordance with a further aspect of the present invention, flushing,priming, and use of the disposable, integrated extracorporeal bloodcircuit is simplified and made more reliable and efficient.

The disposable, integrated extracorporeal circuit 100 is flushed withthe pre-bypass loop 120 in place with CO₂ gas after set-up and prior topriming in order to drive out any ambient air. Referring to FIG. 8, thefluid infusion line 176 is clamped by closing Roberts clamp 197. Inreference to FIG. 14, a portion of the VARD purge line segment 147 isfitted into a fluid in-line (FIL) sensor 404, and the purge line distalend connector 143 is fitted into a clip 426 to orient the fluidisolation filter 149 vertically. The VARD purge line segment 147 is notfitted into the purge valve 410 (preferably a pinch valve as describedfurther below) at this time so that CO₂ gas can flow through the VARD130 and the VARD purge line 141 and purge line segment 147 toatmosphere. The VARD stopcock 135 is set to the open position so thatCO₂ gas can flow through the VARD 130 to atmosphere. The arterial filterpurge port 186 is opened to atmosphere by setting stopcock 187 to theappropriate position so that CO₂ gas can flow through the arterialfilter 180 to atmosphere.

A CO₂ gas delivery line with a microporous bacteria filter is attachedto the 0.250 inch spike at the end of one of priming line branch 151 or153, and the associated Roberts clamp 161 or 163 and the Roberts clamp165 are opened. The Roberts clamps 195 and 197 are also opened. The CO₂gas is then turned on to flow through 0.250 inch PVC tubing priming line159 and then through all of the major components and lines of thedisposable, integrated extracorporeal circuit 100 to atmosphere at aflow rate of 2–3 liters per minute. Upon completion, the CO₂ gas isturned off, and the VARD stopcock 135 is closed. The 0.250 inch primingline 151 or 153 is disconnected from the CO₂ line, and the associatedRoberts clamp 161 or 163 is clamped again.

Priming

The prime volume of the disposable, integrated extracorporeal bloodcircuit 100 preferably is roughly about 1000 ml or less. Preferably, thedisposable, integrated extracorporeal blood circuit may be primed usinga single one-liter intravenous bag 380 of prime solution, e.g., a salinesolution. However, two prime solution bags 380 and 390 are preferablyprovided and filled with prime solution for use in initial priming or asrequired during the bypass procedure.

The steps of priming the disposable, integrated extracorporeal circuit100 with the bypass circuit 120 fitted in place are shown in FIGS. 9–11.The blood pump 150 is turned off during initial stages of priming andturned on at the end stage of priming. The VARD purge line 141 (shown inpart) is extended upward so that purge line distal end connector 143 islocated about at the elevation of hanger 360 so that air accumulating incan VARD 130 can escape through the open purge line distal end connector143. The arterial line 114 is at a slightly higher elevation than thevenous return line 112 due to the U-shape of the bypass circuit 120. Asprime solution is fed by gravity through the priming line 159, the primesolution enters the circuit low elevation at “T” style connector or line158 and upward fills the components and lines of the extracorporealblood circuit 100 in a sequence illustrated in FIGS. 9–11. Oxygenator160 and the oxygenator outlet line 188 are antegrade filled, i.e.,upward filled with the normal direction of blood flow when blood pump150 is operating. Blood pump 150, VARD 130, venous return line 112,utility connector 110, bypass circuit 120, and arterial line 114 areretrograde filled, that is upward filled against the normal direction ofblood flow when blood pump 150 is operating.

The prime solution bags 380 and 390, filled with prime solution, and theempty sequestering bag 370 are hung on the IV hangar 360 in preparationfor priming. The Roberts clamps 382 and 386 can be left open as shown inFIG. 9 because the spike ports 372 and 376 are not yet perforated. Thebranch 177 of the “Y” style connector attached to therecirculation/cardioplegia line 174 employed during cardioplegia remainsplugged, and the temperature sensor ports 171 and 126 are sealed.Initially, Roberts clamps 384, 161, 163, 165, 194 and 195 are closed,and the Roberts clamp 197 remains open.

As shown in FIG. 9, the 0.250 inch spikes of the lines 151 and 153branching from the 0.250 inch priming line 159 are inserted through thepenetrable seals of the prime solution bags 380 and 390, respectively. Abranch 175 of the “Y” style connector attached to therecirculation/cardioplegia line 174 is coupled to the bayonet accessport at the free end of the bag line 374 of the sequestering bag 370.The remaining ports and stopcocks remain as set at the end of theflushing operation. Tubing clamps, e.g., hemostats, are applied at aboutpoint C1 of the branch of the “Y” style line 156 that is coupled at itstrunk to the blood pump inlet 152 and at about point C2 in theoxygenator outlet line 188 to prevent flow of prime solution into thechambers of VARD 130 and arterial blood filter 180, respectively.

Then, the Roberts clamps 161 and 165 are opened to gravity fill the pump150, the oxygenator 160, the fluid infusion line 176, and the oxygenatoroutlet line 188 with prime solution draining from prime solution bag 380while the clamp is maintained at C1. The Roberts clamp 197 is opened (ifnot already open) while the fluid infusion line 176 extends upwardsupported in one vertical raceway 222 as shown in FIG. 8. The upwarddirection of the branch of “Y” style line 156 coupled to the fluidinfusion line 176, and the upward support of the fluid infusion lineprovides a “standpipe” that facilitates driving air out of the bloodpump 150 and retrograde filling of the blood pump 150 and fluid infusionline 176 with prime solution. The Roberts clamp 197 is closed as shownin FIG. 9 after the fluid infusion line 176 is filled with primesolution. Antegrade filling of the oxygenator outlet line 188 isassisted by unclamping the tubing clamp at about C2 and applying thetubing clamp again at about C2 when prime solution reaches the arterialfilter inlet 182.

Turning to FIG. 10, the 0.250 inch spike at the end of the fluidinfusion line 176 is then inserted into the bayonet port at the free endof bag line 376 extending from sequestering bag 370. One of the Robertsclamps 384 and 195 is closed as shown in FIG. 10 when prime solutionrises through the recirculation/cardioplegia line 174 and begins to fillthe sequestering bag 370. Thus, upward filling of the oxygenator 160 andthe pump 150 and the fluid infusion line 176 andrecirculation/cardioplegia line 174 is accomplished to drive air bubblesupward and out of the venous blood pump 150 and oxygenator 160 and thelines coupled therewith as shown by the cross-hatching in FIGS. 9 and10.

The tubing clamp at C1 is also released in FIG. 10 to allow the primesolution to rise upward through the VARD outlet 136, to fill the VARD130, and to pass through the VARD inlet 132 into the venous return line112. The prime solution rises upward through the venous return line 112,the utility connector 110, the TMC 38 BioTrend® connector 108, thebypass circuit 120, the arterial line 114 passing through the blood flowtransducer connector 190, and through the arterial filter outlet 184into the chamber of the arterial filter 180. The check valve 119prevents prime solution from rising from the utility connector 110through the arterial filter recirculation line 118 to the stopcock 187.The housing of the arterial filter 180 is preferably transparent so thatthe upward rising prime solution and any air bubbles can be seen. Thestopcock 187 is closed when the prime solution starts to escape thearterial filter purge port 186.

The stopcock 135 is also opened so that prime solution begins to fillthe upwardly extending VARD purge line 141 as shown in FIG. 10 and isthen closed. As noted above, the VARD purge line 141 is supported toextend upward during priming by one vertical raceway 222 of the C-shapedarm 202 as shown in FIG. 8 so that air can escape through VARD purgeline 141 and to atmosphere. At least the upper part of the housing ofthe VARD 130 is preferably transparent so that any air bubbles can beseen. The purge line segment 147 is inserted into the purge line pinchvalve 410 to close the purge line segment 147 as the VARD purge line 141begins to fill with prime solution. The stopcock 135 remains open, andthe stopcocks 196, and 125 are opened. Stopcock 125 is then closed whenprime solution rises and fills the venous blood pressure monitoring line116 and the pressure isolator 117.

Thus, air is driven upward and out of the chambers of the VARD 130 andthe arterial filter 180 as they are filled with prime solution as shownin the cross-hatching in FIG. 10. The Roberts clamps 161 and 165 remainopen. In FIG. 11, the tubing clamp is applied at about C3 is removed toallow priming fluid to drain from prime solution bag 380 through thepriming line 159, the pump 150, and the fluid infusion line 176 into thesequestering bag 370. The sequestering bag 370 is filled with sufficientprime solution to enable priming of the cardioplegia circuit through thecardioplegia port 177. It may be necessary to open Roberts clamp 163 todrain prime solution from the second prime solution bag 390 in fillingsequestering bag 370.

The wall vacuum source is then coupled to the purge line distal endconnector 143 via the vacuum line and liquid trap to provide a regulated−215 mmHg vacuum through the VARD purge line 141 when the pinch valve410 is opened. The VARD sensor cable 450 is attached to the sensorelement connector on VARD 130 and the cable connector 454 on the housing402 of the AAR controller 400. The Roberts clamp 165 is closed, thetubing clamp at C2 is released, and the venous blood pump 150 is turnedon at minimum flow.

The three stopcocks of sampling manifold 115 are then set to allowarterial blood flow and air to be drawn by the venous blood pump 150through the arterial blood sampling line 172, check valve 121, thesampling manifold 115, line venous blood sampling line 106 and into theutility connector 110. Air is thereby vented out of the arterial filterrecirculation line 118 and sampling manifold 115 through the utilityconnector 110 into the VARD 130 by the venous blood pump 150. The airthat accumulates in the VARD upper chamber is then suctioned out throughthe line VARD purge line 141 when the AAR controller pinch valve ismanually opened as described below. Arterial filter 180 and fitting 208can be detached, inverted, and gently tapped so that the pumped primesolution moves any air in the arterial filter 180 out through thearterial filter outlet 184 and to the VARD 130. The arterial filter 180and fitting 208 are then reinstalled into the fitting 208 and inspectedvisually for evidence of any air bubbles that may require repeating ofthe inverting and tapping steps. The stopcocks of the sampling manifold115 is then reset to block flow.

At this point, the extracorporeal blood circuit 100 is primed. Thepre-bypass loop 120 is disconnected, and table lines coupled to cannulaeor elongated cannulae (herein referred to generally and collectively astable lines) can be attached to the quick disconnect connectors 102 and104. The oxygen lines are coupled to the access ports 162 and 164 andthe water lies are coupled to the water inlet 166 and water outlet 168of the oxygenator 160.

AAR System and Method

In a further aspect of the present invention, an improved AAR system andmethod are provided that are capable of sensing and removing air andblood froth from VARD 130 while removing a minimal amount of liquidblood. The AAR system comprises the VARD 130 depicted in greater detailin FIGS. 12A, 12B and 13 functioning with an AAR controller 400 of thepresent invention depicted in FIGS. 14–15. The AAR system is capable ofremoving a continuous stream of air injected into the venous return line112 at a rate of up to about 200 ml/min from VARD 130 after the AARcontroller 400 is connected with the VARD 130 and made operational asdescribed further below in reference to FIGS. 16–57. The AAR systempreferably can handle a maximum rate of air removal of about 400 ml/minof air and blood froth. In addition, the AAR system is capable ofremoving a 50 cc bolus of air injected into the venous return line 112over several seconds from VARD 130. The VARD 130 is advantageouslyemployed with the AAR controller 400 performing the methods describedherein, but the principles of design and operation of VARD 130 may bealternatively employed in other contexts.

The VARD 130 is preferably a modified conventional arterial blood filterhaving upper and lower air sensors. For example, VARD 130 may be amodified AFFINITY® Arterial Filter sold by Medtronic, Inc. Air entrappedin the venous blood is actively removed by a vacuum applied to the purgeport 134 of VARD 130 through the VARD purge line 141. The VARD 130preferably comprises a housing 142 having a hollow volume displacer 146comprising an inverted cone that extends down into center of the venousblood chamber 140 from an upper end wall of the housing 142 and definesan annular upper VARD inlet chamber 148 and an annular lower VARDchamber 140. The housing 142 incorporates components enabling thefiltering of the venous blood drawn through it by blood pump 150 and thedetection and automatic removal of air and froth rising to the VARDinlet chamber 148. The lower cap or portion of housing 142 including theoutlet port 136 are not shown in FIGS. 12A and 12B.

Normally, the lower VARD chamber 140 and the upper inlet chamber 148 ofVARD 130 is filled with blood as venous blood pump 150 draws venousblood through upper inlet 144 coupled to venous return line 112 intoVARD inlet chamber 148, through an internally disposed filter element(not shown) and out of the lower VARD outlet 136. A screen or otherconventional bubble-trapping device may be inserted in venous bloodchamber 140 below the VARD inlet chamber 148 to trap air bubbles in theblood stream and cause them to stay in the VARD inlet chamber 148. TheVARD 130 differs from the arterial blood filter 180 in that itincorporates a sensor array 138 comprising four piezoelectric elements138A, 138B and 138C, 138D that are arranged in orthogonally disposedpairs of piezoelectric elements 138A, 138B and 138C, 138D as shown inFIGS. 12A, 12B, and 13 that sense the level of blood within the upperVARD inlet chamber 148 or in the lower VARD chamber 140.

In one embodiment of the present invention, a first or upper pair ofultrasonic piezoelectric elements 138A and 138B is disposed across thepurge port 134 and a second or lower pair of ultrasonic piezoelectricelements 138A and 138B is disposed below the VARD inlet chamber 148forming the sensor array 138. The piezoelectric elements 138A and 138Care disposed, preferably by bonding, on the exterior surface of thecavity inside the volume displacer 146. The piezoelectric elements 138Band 138D are disposed, preferably by bonding, on the exterior surface ofthe housing extending between the upper portion of the VARD inletchamber 148 to the purge port 134 and the housing 142, respectively.

The piezoelectric elements 138A, 138B and 138C, 138D utilized herein maypreferably be formed employing conventional, rectangular, piezoelectriccrystal layers of a thickness selected to be resonant in the range of 1to 3 MHz, and specifically about 2.25 MHz and mounted as depicted inFIGS. 12A and 12B and described below. Conductive thin film electrodesare deposited, plated or otherwise applied to the major surfaces of thepiezoelectric crystal layers, and conductors are welded or soldered tothe electrodes. As is well known, such a piezoelectric element can beexcited to oscillate in a thickness mode by an RF signal applied, viathe conductors and electrodes, across the thickness of the crystallayer. The resulting mechanical vibration of the transmittingpiezoelectric element is transmitted though a fluid chamber or conduit.Ultrasonic vibrations emitted by the transmitting piezoelectric elementpass through the liquid in the chamber or conduit to impinge upon thereceiving piezoelectric element. The receiving piezoelectric elementvibrates in sympathy with the ultrasonic vibrations and produces analternating current potential proportional to the relative degree ofvibratory coupling of the transmitting and receiving piezoelectricelements. The degree of coupling of the ultrasonic vibrations abruptlydrops when air is introduced between the transmitting and receivingpiezoelectric elements, and the output amplitude of the signal generatedby the receiving piezoelectric element drops proportionally.

Therefore, one piezoelectric element of each pair 138A, 138B and 138C,138D is used as a transmitting crystal, and the other piezoelectricelement of each pair 138A, 138B and 138C, 138D is used as the signalreceiver. It is preferable to use pairs of piezoelectric elements, one atransmitter and the other a receiver, rather than to employ a singlepiezoelectric element used as both transmitter and receiver, because apair of piezoelectric elements provides a more robust sensing system.The presence of liquid or air between the transmitting piezoelectricelement and the receiving piezoelectric element differentiallyattenuates the transmitted ultrasonic signal in a manner that can bedetected from the electrical signal output by the receivingpiezoelectric element in response to the ultrasonic signal.

The eight conductors coupled to the eight electrodes of thepiezoelectric elements 138A, 138B and 138C, 138D are extended to VARDconnector 454 (depicted schematically in FIG. 12B) mounted on the VARDhousing 142. The distal cable connector 452 of reusable VARD cable 450extending to AAR controller 400 shown in FIG. 14 is intended to becoupled to the VARD connector 454. The VARD cable 450 comprises 10conductors, and the distal cable connector 452 and VARD connector 454comprise 10 contact elements. Eight of the cable conductors are coupledthrough eight of the mating connector elements with the eight conductivethin film electrodes of the sensor array 138. Two further connectorelements of the VARD connector 454 are electrically in common, and acontinuity check can be performed by the VARD circuitry through the twocable conductors joined when contacting the two connector elements. Inthis way, any cable or connector failure can be immediately detected andan alarm sounded by the VARD 400.

The excitation of the transmitting piezoelectric elements and theprocessing of the signals generated by the receiving piezoelectricelements is performed by an electronic circuit of the AAR controller 400coupled to the cable. A microprocessor or controller of the electroniccircuit of AAR controller 400 utilizes the processed received signals todetermine when the liquid level is below the upper pair of piezoelectricelements 138A, 138B and opens a pinch valve 410 engaging and normallyclosing the silicone rubber purge line segment 147 to allow suction tobe applied through the VARD purge line 141 to purge port 134 to evacuatethe air and froth within the upper VARD inlet chamber 148 below thelevel of the piezoelectric elements 138A, 138B. The vacuum applied atthe purge port 134 overcomes the negative pressure imposed by venousblood pump 150 within VARD inlet chamber 148 and draws out theaccumulated air through the purge port 134. An audible and/or visualwarning may be activated to indicate the presence of air within the VARDinlet chamber 148. For example, an audible and/or visual alarm may beactivated if liquid, e.g., blood or saline, is not sensed forapproximately five seconds. The warning may continue while air is beingremoved. Detection of liquid between the upper pair of piezoelectricelements 138A, 138B causes the controller to close the pinch valve 410to halt the application of vacuum through the VARD purge line 141.

The second, lower pair of piezoelectric elements 138C, 138D located justabove the transition of the venous blood chamber 140 with the VARD inletchamber 148 provides a backup to the first, upper pair of piezoelectricelements 138A, 138B, should the first, upper pair of piezoelectricelements fail. The second, lower pair of piezoelectric elements 138C,138D also provide a way to detect if the liquid level has dropped belowa minimally acceptable level, even though pinch valve 410 has beenopened by the detection of air by the first, upper pair of piezoelectricelements 138A, 138B. A further distinctive audible and/or visual alarmmay be activated if the blood level falls below the second pair ofpiezoelectric elements 138C, 138D.

In one embodiment of the present invention, the piezoelectric elements138A, 138B, 138C, 138D are preferably rectangular in shape and arrangedso that the long axis of the transmitter piezoelectric element 138A,138C is rotated 90° from the long axis of the receiver piezoelectricelement 138B, 138D in the manner shown in FIG. 10. This configurationprovides better transmission overlap at 139 of the transmittedultrasonic signal to the receiver piezoelectric element of the pair.

The piezoelectric elements 138A, 138B, 138C and 138D are alsoillustrated in FIGS. 13B–13E. Each piezoelectric element 138A, 138B,138C and 138D comprises a piezoelectric crystal assembly 428 encasedwithin a nonconductive element housing 432. The element housing 432preferably comprises a lid 435 and a base 433, wherein the base 433 islonger than the lid 435. The lid 435 has an upwardly extending rib asshown in FIGS. 13B and 13C. The sides of base 433 extend past the lid435 as shown in FIG. 13C.

A pair of conductors 434 and 436 extend through the long side of lid 435of the element housing 432 in the configuration of piezoelectricelements 138B and 138D. An alternative pair of conductors 434′ and 436′extend through the short side of lid 435 of the element housing 432 inthe configuration of piezoelectric elements 138A and 138C. In eachconfiguration, the conductors 434, 436 or 434′, 436′ are coupled to thinfilm electrodes formed on the major opposed surfaces of thepiezoelectric crystal layer 428 within the lid 435. The piezoelectriccrystal layer 428 may be formed of any suitable piezoelectric ceramicbearing the opposed surface electrodes. One surface electrode is adheredto the base 433 that is to be applied against the slot side wall of theVARD housing 142.

Preferred ways of mounting the piezoelectric elements 138A, 138B, 138Cand 138D to the VARD housing 142 are illustrated in FIGS. 13D and 13E.Four slots 438A, 438B, 438C, and 438D shaped to conform to the elementhousing 432 are formed on the outer wall of the housing 142. The slots438B and 438D shown in FIG. 13D are shaped to receive the respectivepiezoelectric elements 138B and 138D extending orthogonally to the axisof the VARD housing 142 and the hollow volume displacer 146 as shown inFIGS. 12A, 12B, and 13A. Each slot 438B and 438D, is shaped to receivethe lid 433 that is applied against he housing wall. Stops 439B and 439Dfit against the side of container 435 when the lid 433 is slipped intothe respective slot 438B and 438D against the housing wall. The slots438A and 438C shown in FIG. 13E are formed within the wall of hollowvolume displacer 146 and are shaped to receive the respectivepiezoelectric elements 138A and 138C extending in alignment with theaxis of the VARD housing 142 and the hollow volume displacer 146 asshown in FIGS. 12A, 12B and 13A.

During assembly, the outer surface of the nonconductive element housing432 is coated with a gel adhesive that is cured when exposed to UVlight, for example, and is fitted into the slots 438A, 438B, 438C, and438D. The VARD housing 142 is exposed to UV light to cure the adhesive.

The AAR controller 400 is shown in greater detail in FIGS. 14 and 15comprising an AAR controller operating system that includes AARcontroller circuitry 460 and electrical components coupled thereto tofunction as described further herein. The AAR controller circuitry 460and certain components coupled to the circuitry shown in FIG. 15 arepowered normally by an AC line input 418 to power supply 464 but can bepowered by a backup battery 462 in case of general power failure orfailure of the power supply 464. The power supply 464 comprisesredundant power supply circuits and switching circuitry for selecting anoperable power supply circuit to deliver operating power. The AARcontroller circuitry 460 takes the form of a microprocessor-basedcomputer operating under control of software stored in RAM and can beprogrammed via the programming port 466.

In FIG. 14, a clamp (not shown) on the rear side of housing 402 of theAAR controller 400 is adapted to be attached to the left support arm 322of the reusable circuit holder 300 shown in FIG. 6. After attachment, aperfusionist interface 420 comprising an LCD screen 430 and a controlpanel 440 are disposed outward to facilitate seeing the displayed textin LCD screen 430 and warning lights and to facilitate use of the softkeys of the control panel 440.

The FIL sensor 404 disposed on the upper surface of the housing 402 hasa hinged cover or latch 405 extending across an upward opening slot sothat the slot cross-section area is constant when the latch 405 isclosed. The latch 405 preferably has a downward extending bar thatextends into the FIL sensor upward opening slot. In use, the FIL sensorlatch 405 is opened, the VARD purge line 141 is extended laterallyacross the oxygenator 160, a portion of the compressible VARD purge linesegment 147 is fitted into the FIL sensor slot, and the FIL sensor latch405 is closed. The portion of the compressible VARD purge line segment147 fitted into the FIL sensor slot is compressed by the downwardlyextending bar when the latch 405 is closed so that the tubing wall ispressed tightly and uniformly against the opposed side walls of the FILsensor slot. The purge line distal end connector 143 is fitted into theupward opening slot of clip 426 with the isolation filter 149 and thevacuum sensor line 145 extending vertically.

The pinch valve 410 disposed on the upper surface of the housing 402comprises upper and lower members 406 and 408 that define a side openingslot between them that a further section or portion of the compressibleVARD purge line segment 147 can be fitted into. A purge line guide post409 also extends upward from the upper surface of the housing 402 sothat the purge line segment 147 is routed between the purge line guidepost 409 and the pinch valve 410 when the pinch valve 410 is closed andthe purge line segment 147 is not yet positioned in the pinch valveslot.

A pinch rod 458 extends upward from within the AAR controller housing402 under spring tension. The pinch rod 458 extends transversely intoand across the slot between the upper and lower members 406 and 408. Thepinch rod 458 can be moved downward out of the pinch valve slot bydepression of mechanical release button 412 to insert a portion of thecompressible VARD purge line segment 147 into the slot. The purge lineguide post 409 and the FIL sensor slot holding another portion of theVARD purge line segment 147 as described above keep the portion of theVARD purge line segment 147 within the pinch valve slot when the pinchrod 458 is later moved downward out of the pinch valve slot as describedbelow.

The pinch rod 458 again extends upward under spring tension to compressthe section of compressible VARD purge line segment 147 closed uponrelease of the mechanical release button 412. The pinch rod 458 cannotextend all the way across the slot between the upper and lower members406 and 408 when a portion of the purge line segment 147 is fitted intothe slot. The pinch rod 130 can be retracted by again depressingmechanical release button 412. The pinch rod 130 extends through thecore of a solenoid coil that is powered under the control of thecircuitry of the AAR controller 400 to draw the pinch rod 458 downwardto the pinch valve open position.

The tubing of purge line segment 147 inserted into the pinch valve andFIL sensor slots is composed of a soft, biocompatible material having asuitable durability and resilience, e.g., silicone rubber tubing.Preferably, the silicone rubber tubing of purge line segment 147 has a0.250 inch ID and a 0.375 inch OD, and the silicone rubber tubing hassufficient resilience to restore the lumen diameter to at least ¾ of itsnominal lumen diameter upon retraction of the pinch rod 130.

Typically, if air is sensed in the VARD 130, fluid would not be sensedin the purge line segment 147 by the FIL sensor 404, and so the pinchvalve would close 410 before blood is suctioned all the way to the FILsensor 404. However, the intermittent detection and purging of airthrough the purge line 141 will in time draw boluses of blood orblood-air froth out of the VARD 130 through the purge line segment 147such that detection of blood by the FIL sensor 404 could cause the AARoperating system to inappropriately close the pinch valve 410 while airis still sensed in the VARD 130. Therefore, preferably the sensor outputsignal of the FIL sensor 404 is processed over a time window thatminimizes this possibility.

More particularly, the FIL sensor 404 is preferably a high frequencyacoustic sensor employing a piezoelectric element disposed on one sideof the FIL sensor slot that is energized to emit acoustic energy and apiezoelectric element disposed on the other side of the FIL sensor slotthat is coupled to FIL sensor signal processing circuitry to function asa receiver element. The receiver element provides a FIL sensor outputsignal that varies in amplitude as a function of the modulation of theemitted acoustic energy by air or fluid in the portion of the purge linesegment 147 within the FIL sensor slot. The FIL sensor output signal isattenuated by fluid in the portion of the purge line segment 147 withinthe FIL sensor slot. The FIL sensor output signal is sampled at apredetermined sampling rate, and the sampled amplitude is compared to athreshold set for air. Generally speaking, a count in a hardware orsoftware counter of the AAR circuitry 460 (FIG. 15) is incremented ordecremented by the high or low output of the comparator. For example,the count may be incremented each time that the sampled FIL sensoroutput signal is attenuated by fluid in the line and is decremented orreset to zero each time that the sampled FIL sensor output signal has anamplitude that is not attenuated by air in the line. A FIL error stateis only declared when a predetermined count is met. Therefore,intermittent boluses of fluid, particularly the patient's venous blood,and blood-air froth do not trigger declaration of the FIL error state.

The distal end of the vacuum sensor line 145 is attached to a vacuumsensor input 414 on a first side of the housing 402 as shown in FIG. 14.An audible tone generator 416 is mounted to the first side of thehousing 402. An AC power cord 418 is attached to a receptacle in thesecond side of the housing 402. The reusable VARD sensor cable 450containing the eight conductors attached to the eight surface electrodesof the piezoelectric elements 138A, 138B, 138C and 138D and the twocontinuity checking conductors extends between the cable connector 452and the cable connector 422 on the second side of the housing 402. Thepurge line segment 147 fitted into the slots of the FIL sensor 404 and apinch valve 410 is preferably at the same level as the VARD purge port134, and the height of the AAR controller 400 is adjustable by adjustingthe electronics arm assembly 314 along the mast 302.

The soft keys in the control panel 440 depicted in FIG. 14 include an“ON” key and an “OFF” key that can be depressed by the perfusionist topower up and power down, respectively, the AAR controller circuitry 460and the various sensors and electrical components coupled to thecircuitry. A “RESET” key can be depressed at any time by theperfusionist to reset the controller signal processor and restart theAAR operating algorithm in the Self-Test Mode described further below. Ayellow “Caution” light and a red “Alarm” light are lit when the signalprocessor determines certain respective caution and alarm conditions.The audible tone generator 416 emits respective audible caution andalarm tones. A “MUTE” switch can be depressed to silence the audibletones. The “STANDBY” and “AUTO” keys can be depressed to initiate therespective Standby and Automatic Modes described further below. The“MANUAL” soft key can be depressed to open the pinch valve 410 in theStandby and Automatic Modes if the AAR operating system is being poweredby the power supply 464 and only for as long as the “MANUAL” soft keyremains depressed. The function keys F1, F2, and F3 can be depressed inresponse to a message displayed along the lower edge of the LCD screen430 in alignment with the particular function key.

Referring to FIG. 15, the pinch rod 458 is axially aligned with andcoupled to a solenoid core that moves downward into housing 402 when thesolenoid coil is energized or when the mechanical release button 412 ismanually depressed. A solenoid driver 470 is selectively actuated by AARcontroller circuitry 460 automatically or when the MANUAL key isdepressed to drive the pinch rod 458 downward overcoming the biasingforce of the spring. Preferably, a plurality of optical pinch valvesensors 472 are provided within the housing 402 to determine theposition of the downwardly extending pinch rod 458 or solenoid corecoupled to the pinch rod 458. For example, a plurality of holes areformed through the pinch rod 458, and light emitters and photocellsarranged along the length of the pinch rod 458 so that emitted lightpassing through a particular hole is detected by a photocell of anoptical position sensor to generate an output signal. The output signalsof the optical position sensors 472 signify whether the pinch rod 410 isin a fully open position, a closed position against the portion of thepurge line segment 147 fitted into the pinch valve slot, and a fullyclosed position extending all the way across the pinch valve slot. Theoutput signals of the pinch rod position sensors 472 are also employedto confirm that the pinch rod 458 has moved from one position to theother position in response to the applied appropriate command or is inan improper position and malfunctioning. Pinch rod positions other thanthese fully open, closed or fully closed positions that are sensed atinappropriate times are considered error positions or states, and anaudible and visible alarm are emitted and a valve error message isdisplayed on LCD screen 430 as described below.

The purging operation in the Automatic Mode is dependent upon a numberof conditions and sensor input signals that effect the automatic openingand closing of the pinch valve 410. The AAR controller circuitry 460 andthe solenoid that moves the pinch rod 458 must be powered by anoperational power supply 464 rather than the backup battery 462 in orderto automatically open the pinch valve 410. Generally speaking, theautomatic opening of the pinch valve 410 in the Automatic Mode takesplace when output signal generated by one of the upper air sensorpiezoelectric elements 138A, 138B (or the lower air sensor piezoelectricelements 138C, 138D) indicates that air is present in the VARD inletchamber 148 and when specific error states are not declared. Theconditions and states are continually monitored, and a declared errorstate inhibits the opening of the pinch valve 410, that is interruptsand closes the purge valve if purging has already started or preventsthe purge valve opening if purging has not started. The depression ofthe OFF, STANDBY and RESET keys also both interrupt the opening of thepinch valve 410 and terminate the Automatic Mode. Mechanical opening ofthe purge valve 410 is possible at any time.

The error states declared in the Automatic Mode that inhibit opening ofthe purge valve 410 are indicated by error messages displayed on the LCDscreen 430 depicted in FIGS. 50–56 and emission of light and soundCautions that alert the perfusionist to take appropriate correctiveaction. The declared error states include low suction (FIG. 55), failureof the VARD sensors (FIG. 54), a pinch valve failure (FIGS. 50–52),failure of the VARD cable continuity check (FIG. 56), and a FIL errorstate (FIG. 53). A vacuum threshold level must be met by the vacuum inthe vacuum line segment 147 measured through vacuum sensor line 145 andisolation filter 149 by the vacuum sensor coupled to vacuum sensor input414. The failure of one or more of the piezoelectric elements 138 isdeclared in the event that the air sensor signal from the receiver oneof the lower piezoelectric element 138C or 138D signifies detection ofair while the air sensor signal from the receiver one of the upperpiezoelectric element 138A or 138B signifies detection of fluid. A pinchvalve error state is declared when the pinch rod 458 does not move to orfrom the open or closed position or is in an improper position. A VARDcable connection failure is declared when the continually check resultsin an open circuit as described above. A FIL error state is declaredwhen blood is sensed in the purge line segment 147 for the required timeas described above. The perfusionist then must take appropriate action,which may include replacing the AAR controller 400 or the VARD cable 450or manually opening the pinch valve to purge air.

If the AAR controller circuitry 460 is powered by power supply 464, theoperator can manually evacuate the air by depressing the MANUAL key onthe control panel 440 if no error state is declared. When the MANUAL keyis depressed in the absence of an error state, power is supplied to thesolenoid to draw the pinch rod 458 down to open the pinch valve 410thereby allowing the vacuum source coupled to nozzle 143 to remove airfrom the VARD 130 through the VARD purge line 141. The LCD screen 430displays “VALVE OPEN” while the MANUAL key is depressed, although theAutomatic Mode remains enabled when pressing the MANUAL key. Theperfusionist releases the MANUAL key to close the pinch valve 410 onceair has been removed from the VARD 130. The Alert message “AIR IN VARD”automatically clears from the LCD screen 430. The yellow LED stopsflashing and the audible tone stops.

The method of operation of the AAR system in the Self-Test, Standby, andautomatic (AUTO) operating modes and in response to detected normal andabnormal conditions and battery power states is illustrated in theflowcharts of FIGS. 16A–16B and 17A–17B and the LCD screen displays inFIGS. 18–57. It is assumed that the above-described components of thedisposable, integrated extracorporeal blood circuit 100 are spatiallyarranged and supported in 3-D space as shown in FIG. 5 in relation tothe patient on the operating table by the disposable circuit supportmodule 200 and reusable circuit holder 300. It is also assumed that alloperational connections, sensors, lines and the like, are made withcomponents and lines of the extracorporeal blood circuit 100 asdescribed above, and that the priming solution bags 380 and 390 and thesequestering bag 370 are supported by the IV hangar 360 with the linesconnected in preparation for priming as shown in FIG. 9. The reusableVARD sensor cable 450 extends from the VARD connector 454 laterallythrough channel 332 and is connected with the AAR controller VARDconnector 422. At this point, the purge line segment 147 is routed toextend upward for priming, and the VARD controller 400 is connected toan AC power line.

Turning to FIG. 16A, the AAR controller circuitry 460 commences aself-test operating mode in step S102 when the “ON” key is depressed instarting step S100. A solid LCD display appears in LCD display screen430 for 2 seconds, for example, followed by a display of the version ofthe installed software as shown in FIG. 18, to verify proper operationof the LCD display screen 430. Furthermore, both the yellow (Caution)and red (Alarm) LEDs on control panel 440 flash momentarily to verifyproper operation when the “ON” key is depressed, and a series of “chirp”sounds are emitted by the audible tone generator 416 for several secondsto verify proper operation. The perfusionist is expected to observe orhear the failure of these components and to check the power lineconnection and backup battery, repeat start up, and to replace the AARcontroller 400 if does not pass these initial self-tests.

Further self-test operations ensue in step S102 if these components ofthe AAR controller 400 function properly. The backup battery 462,software, and pinch valve 410 are subjected to self-test in step S102 totest proper state or function upon power up. Failure messages shown inFIGS. 30–36 are displayed in step S106 on LCD screen 430 in response tocertain declared self-test failures. The self-tests are repeated in stepS102 if the perfusionist depresses the “RESET” key as detected in stepS108. The perfusionist is expected to take appropriate action in stepS110 if the self-test failure persists, particularly to replace the AARcontroller 400 and start over at step S100 if the self-test failuremessages of FIGS. 30–33 are displayed.

In one of the self-tests, a software cyclic redundancy check (CRC) isrun in step S102 to ensure that the software is functioning correctly.In step S106, the LCD screen 430 displays the message appearing in FIG.30 instructing the perfusionist to replace the AAR controller 400 with abackup unit in step S108 if the CRC failure is declared.

The pinch valve 410 is subjected to mechanical function and softwareself-tests. The pinch valve solenoid 470 is powered in response to asoftware instruction to move the pinch rod 458 upward to the closedposition and downward to the open position. The response and position ofthe pinch rod 458 is detected employing the pinch valve optical sensors472. The LCD screen 430 displays the message of FIG. 31 or FIG. 32 instep S106 if a pinch valve hardware failure is found. The LCD screendisplays the message of FIG. 33 in step S106 if a pinch valve softwarefailure is found. Again, the perfusionist can depress the RESET key perstep S108, and the AAR controller 400 is to be replaced by a backup unitper step S110 if the pinch valve self-test failure is repeated.

The power states of the AAR controller 400 are also determined, and theLCD screen 430 displays one of the messages of FIGS. 34–36 in step S106if a power state failure is detected. While operating algorithm of theAAR controller 400 can be powered by the battery 462, use of line powerapplied to one of the redundant power supply circuits in power supply464 is required to power the solenoid and is otherwise preferred sincethe battery power can deplete during the cardiac bypass procedure. Thepower state self-tests determine whether the AAR controller circuitry460 is being powered by the battery 462 or the power supply 464. Thepower state self-tests also determine that a battery 462 is or is notpresent in its compartment and the current state of depletion of batterypower, if the battery 462 is present. Thus, the perfusionist isinstructed to take the appropriate action per step S110 if the batterypower is low (FIG. 34), is not present (FIG. 35) or if battery backup is“ON” (FIG. 36) indicating a power supply failure or mains failure orsimply that the AAR controller power cord is not plugged into mainspower. The LCD screen displays of FIGS. 34–36 highlight the F3 key withthe word “CONTINUE?” indicating that the perfusionist can proceed, ifnecessary, to the Standby Mode and employ the AAR controller 400 inbattery backup, which may be necessary under certain conditions.

The LCD screen 430 displays “NO ERRORS DETECTED” in step S112 as shownin FIG. 19 upon successful completion of the Self-Test mode or uponpressing the F3 key in response to the LCD screen displays of FIGS.34–36. The operating algorithm automatically switches to the StandbyMode in step S114. The LCD screen 430 displays the message shown in FIG.20 indicating that the pinch valve is in the normally closed (pinch rod458 is up) state and that highlights the F2 key as “MENU” at the bottomof the LCD screen 430 unless an error state is immediately detected instep S116. Various conditions are also monitored when the operatingalgorithm is in the Standby Mode of step S114, and any correspondingerror states are detected in step S116. In step S118, one of the errormessages of FIGS. 37–42 is displayed on LCD screen 430, the Caution LEDlight is flashed, and the Caution note sounds. The MUTE key can bedepressed to halt emission of the Caution sounds. The perfusionist cantake appropriate action in step S120. The operating algorithm remains inthe STANDBY Mode while action is taken to correct the condition causingthe declaration of an error state or condition unless it is necessary toreplace the AAR controller 400. In that case, the replacement AARcontroller is installed and connected as described above in step S100,and the Standby Mode of step S114 is again entered upon successfulcompletion of steps S102–S112.

For example, a VARD cable continuity check is periodically conducted,and the message of FIG. 37 is displayed if the VARD cable connector 452(FIG. 14) is not connected to the VARD connector 454 (FIG. 12B) asindicated by the failure of the continuity check performed in block 468(FIG. 15). The VARD cable 450 can be reconnected or replaced in stepS120.

The message of FIG. 38 is displayed on LCD screen 430, and thecorresponding Caution light and sound emitted when air is detectedbetween the lower piezoelectric elements 138C, 138D and/or upperpiezoelectric elements 138A, 138B. The detection of air in VARD 130 isnot an error state per se, and purging of the air is possible asdescribed below.

The power states are monitored, and one of the messages of FIGS. 40, 41,and 42 is displayed if the corresponding power state failure isdetected, and the perfusionist can choose to ignore these error states.

The error message of FIG. 39 may be displayed and the correspondingCaution light and sound emitted when suction is not sensed at suctionport 414. In this way, the operability of the vacuum sensor or theconnection of the vacuum sensor line 145 to the suction port 414 can beascertained. However, the vacuum source is typically disconnected atthis point so that further tests of the FIL sensor can be conducted asdescribed below.

The displayed messages of FIGS. 37–42 also highlight the F2 key as“MENU” at the bottom of the LCD screen 430. The perfusionist can proceedto depress the F2 key from any of the displayed messages of FIGS. 20 and37–42. If the perfusionist depresses the F2 key, the LCD screen 430displays the message of FIG. 21 presenting three choices “LANG” (chooselanguage) “SENSOR” (run FIL sensor test), and “RETURN” (go back to theFIG. 20 LCD screen display) for the keys F1, F2, and F3, respectively.

If the perfusionist depresses the F1 key, a choice of languages appearsin the LCD screen display of FIG. 22 that the perfusionist can scrollthrough by repeatedly depressing the F1 or F2 key until the appropriatelanguage is displayed, whereupon the perfusionist can then depress theF3 key to continue in the displayed language.

At this point, the perfusionist should test the operation of the FILsensor 404 as indicated by the F2 key in the LCD screen display of FIG.21. A test fluid tube in a diameter corresponding to the material anddiameter specifications of the purge line segment 147 and that is emptyof fluid can be temporarily placed passing through the FIL sensor 404.The perfusionist fits the tube into the FIL sensor 404, closes thesensor latch, and depresses the F2 key in the LCD screen display of FIG.21 to initiate detection of the absence of fluid in the test tube, andthe successful detection of air is indicated in the LCD screen displayof FIG. 23.

It is also desirable to determine that the FIL sensor 404 can accuratelydetect fluid in the purge line segment 147 when it is placed to passthrough it as shown in FIG. 14. So, the perfusionist depresses the F3key designated “RETURN” to return to the LCD screen display of FIG. 20and then depresses the F2 key to advance to the LCD screen display ofFIG. 21. The perfusionist fills the test fluid tube with saline or waterand places the fluid filled test tube passing through the FIL sensor404. The FIL sensor latch is closed to apply uniform pressure againstthe fluid filled test tube, and the perfusionist again depresses the F2key to conduct the test. The successful detection of fluid is indicatedin the LCD screen display of FIG. 24, and the F3 key designated “RETURN”is then depressed to return to the LCD screen display of FIG. 20.

The AAR controller 400 is replaced by a backup unit and the process isrestarted in step S100 if “AIR” or “FLUID” is inappropriately displayedin the messages of FIGS. 23 and 24, respectively, during the FIL sensortests. The message of FIG. 20 is displayed on the LCD screen 430 uponsuccessful completion of the FIL sensor tests. The disposable,integrated extracorporeal blood circuit 100 is then prepared for primingand primed as described above with respect to FIGS. 9–11 while the AARcontroller 400 is in the Standby Mode.

The AAR system is employed in the concluding stages of priming asdescribed above to complete the evacuation of air from the componentsand lines of the disposable, integrated extracorporeal blood circuit100. The VARD stopcock 135 is opened (if not already open). Theperfusionist opens the latch over the FIL sensor 404 and manuallydepresses the mechanical release button 412 to depress the pinch rod 458downward. Portions of the purge line segment 147, partly filled withprime solution, are placed as shown in FIG. 14 fitted into the FILsensor 404, the pinch valve 410, and the clip 426, with the vacuumsensor line 145 extending vertically. The perfusionist closes the latchover the FIL sensor 404 that applies uniform pressure to the portion ofthe purge line segment 147 trapped therein, and releases the mechanicalrelease button 412 to allow the pinch rod 458 to rise upward and pinchthe portion of the purge line segment 147 trapped therein.

The perfusionist attaches the free end of the vacuum sensor line 145 tothe vacuum sensor input 414. The vacuum sensor line 145 is attached tothe vacuum sensor input 414, and the purge line distal end connector 143is coupled to a vacuum source, preferably through a vacuum lineincluding a shut-off valve and the liquid trap. The shut-off valve isopened, the vacuum source regulator is adjusted to provide the specifiedvacuum (−225 mm Hg in this instance), and the error message of FIG. 39should discontinue at this point.

Height adjustments are made to electronics arm assembly 314 along themast 302 of FIG. 6 to ensure that the purge line segment 147 mounted atthe top of the AAR controller 400 is at about the same height as theVARD purge port 134.

In this STANDBY state, the standby message of FIG. 20 will be normallydisplayed absent any detected errors. It would then be expected that themessage of FIG. 38 is displayed and the corresponding Caution light andsound emitted when air is detected between the VARD air sensors. In theStandby Mode, the pinch valve 410 remains closed and is notautomatically opened when air is sensed in the VARD 130. Theperfusionist can selectively open the pinch valve 410 to purge air fromthe VARD 130 by depressing the MANUAL key (only if none of the powerstate failures are detected) or by depressing the mechanical releasebutton 412 to depress the pinch rod 458 downward. The LCD screen 430displays the message depicted in FIG. 25 when the MANUAL key isdepressed and displays the message depicted in FIG. 26 when themechanical release button 412 is depressed. The Caution light and soundare discontinued when air is no longer detected between the upperpiezoelectric elements 138A, 138B.

After priming is completed, the operating algorithm remains in theStandby Mode, and the patient is prepared for cardioplegia and/or bypassas described above. The perfusionist can then depress the AUTO key toinitiate the Automatic Mode of operation of the AAR controller 400 andVARD 130 during the delivery of cardioplegia and during bypass. Asindicated in FIG. 16A, certain “transition” conditions are tested instep S124 when the AUTO key depression is detected in step S122. Thetransition error state messages that are detected in step S126 aredisplayed in step S128, and appropriate corrective action may have to betaken in step S130 before the Automatic Mode can be entered from stepS126. The algorithm remains in the Standby Mode of step S114 after thecorrective actions are taken in step S130 and ready to repeat thetransition tests in step S124 upon subsequent depression of the AUTO keydetected in step S122. The algorithm is restarted at step S100 with areplacement AAR controller 400 installed and connected as describedabove, if the AAR controller 400 must be replaced, and the Standby Modeof step S114 is again entered upon successful completion of stepsS102–S112.

The VARD cable continuity is checked again in step S124, and the messageof FIG. 43 is displayed on LCD screen 430 in step S128 if continuity isnot found. The VARD cable 450 is either connected again or replaced andre-connected. The F3 key is depressed to return to step S114 and theAUTO key is depressed to again check for VARD continuity. If the erroris repeated, the AAR controller 400 is to be replaced by a backup unitthat is installed and connected as described above in step S100, and theStandby Mode of step S114 is again entered upon successful completion ofsteps S102–S112.

The presence or absence of a portion of the purge line segment 147 inthe pinch valve 410 is determined in step S124 from the position of thepinch valve rod 458. A portion of the purge line segment 147 within thepinch valve opening prevents the pinch valve 458 from being urged all ofthe way across the pinch valve opening, and the position of the pinchrod 458 is detected by the optical sensors 472. The message of FIG. 44is displayed on the LCD screen 430 in step S128 if the purge linesegment 147 is not detected in this manner within the slot of the pinchvalve 410. The perfusionist repositions the purge line segment 147 anddepresses the F3 key to return to step S114. The AUTO key is againdepressed to check for presence of the purge line segment 147. If theerror is repeated, the AAR controller 400 is to be replaced by a backupunit that is installed and connected as described above in step S100,and the Standby Mode of step S114 is again entered upon successfulcompletion of steps S102–S112.

The AAR controller circuitry 460 also checks for any failure of the airsensor signal processing circuitry to properly respond to and interpretthe air sensor output signal received from the receiver one of thepiezoelectric elements 138A, 138B and 138C, 138D in step S124. It isexpected that the AUTO key will be depressed when the VARD 130 is filledwith fluid following priming, and therefore the air sensor output signalshould not be indicative of air in the VARD 130. In step S124, the airsensor signal processing circuitry can be checked by a software testalgorithm for accuracy in its response to the actual or true air sensoroutput signal and to a test air signal generated internally that isindicative of air in the VARD 130. The air sensor processing circuitryshould not respond by providing a Caution or an Alarm based on the trueair signal and should respond by providing a Caution or an Alarm inresponse to the test air signal. An erroneous response to the true airsignal or the test air signal can be indicative of VARD cable failure ora failure of the air signal processing circuitry. The message of FIG. 45is displayed on the LCD screen 430 in step S128 if an erroneous responseis determined. The VARD cable 450 is either disconnected and connectedagain or replaced by a backup VARD cable 450. The F3 key is depressed toreturn to step S114 and the AUTO key is depressed to again check for airsensor signal circuitry or cable conductor integrity. If this error isrepeated, the AAR controller 400 is to be replaced by a backup unit thatis installed and connected as described above in step S100, and theStandby Mode of step S114 is again entered upon successful completion ofsteps S102–S112.

In a further transition test, the output signals of the pinch valveoptical sensors 472 are processed, and a logical conclusion is derivedthat the pinch rod 458 is in the proper closed position pressed againstthe portion of the purge line segment 147 within the pinch valve slot.The message of FIG. 46 is displayed on the LCD screen 430 if the pinchrod 458 is not detected in the proper closed position. The AARcontroller 400 is to be replaced by a backup unit that is installed andconnected as described above in step S100, and the Standby Mode of stepS114 is again entered upon successful completion of steps S102–S112. Themessage of FIG. 44 is displayed if the pinch rod 458 is detectedextending across the pinch valve slot, and the purge line segment 147 isto be repositioned within the pinch valve slot.

The vacuum or suction that is provided through the vacuum line connectedto the purge line distal end connector 143 also continues to be checkedin step S124 via vacuum sensor line 145 attached to the vacuum sensorinput 414. The message of FIG. 47 is displayed on the LCD screen 430 instep S128 if the vacuum is low. The perfusionist is to take appropriateaction in step S130 to adjust and independently test the vacuum throughthe vacuum sensor line 145, check the connection of the vacuum sensorline 145 to the vacuum sensor input 414, and depress the F3 key toreturn to the Standby Mode in step S114.

Turning first to FIG. 16B, the conditions that result in declaration oferror states displayed by the error messages of FIGS. 50–56 aremonitored in step S132 while the purging operations are conducted instep S150 as expanded in steps S160–S196 of FIGS. 17A and 17B. In FIG.16B, the error monitoring and response operations and the actions takenby the perfusionist are depicted in parallel with the air purgingoperations since declared error states and actions of the perfusionistcan interrupt or inhibit purging. The perfusionist can interrupt theAutomatic Mode by depressing either the STANDBY key in step S152,returning to step S114 or the OFF key in step S154 shutting the AARcontroller algorithm down in step S156.

In FIG. 16B, the error messages shown in FIGS. 50–56 are displayed onLCD screen 430 in step S136 in place of the message of FIG. 27 when anerror state is declared in step S134, and automatic opening of the pinchvalve 410 is inhibited in step S138. The error messages shown in FIGS.50–52, and 54–56 result from the monitored conditions that cause theabove-described error messages of FIGS. 31, 32, 45, 39, and 43, andsimilar corrective actions are to be taken in step S148. If no errorstates are declared in step S134, and no air is detected in the VARD130, the operation in the Automatic Mode of step S150 results in displayof the message of FIG. 27 by the LCD display screen 430 in step S196.

The error messages of FIGS. 50–54 and 56 offer the option to theperfusionist to continue operation by depressing the F3 key designatedCONTINUE? to “clear” the error message if it is transitory. Thedepression of the F3 key is detected in step S140, and the currentmessage generated in step S150 is displayed in step S142 and theautomatic opening of the pinch valve 144 is enabled. However, steps S132restarts, and the error state is again declared in step S134 if theunderlying error condition is still present. Thus, the opening of thepinch valve 410 may only be transitory.

The perfusionist will then resort to either depressing the RESET key instep S146 to return to the Self Test Mode of step S102 or take theappropriate corrective action in step S148, which may involve replacingthe AAR controller 400 and restarting the algorithm at step S100. Or theperfusionist may simply resort to manually opening the pinch valve bydepressing the mechanical release button 412 or the MANUAL key or tomanually clamping and unclamping the suction line or VARD purge line 141as air is observed in the VARD 130 or venous return line.

The operations in step S150 of FIG. 16B, expanded upon as stepsS160–S196 in FIGS. 17A–17B, depend upon whether the AAR circuitry 460 isbeing powered by the power supply 464 or is being powered by the backupbattery 462, i.e., the operating system is in the battery backup state.In general, the operating system automatically opens the pinch valve 410or responds to the MANUAL key depressed by the perfusionist when theoperating system is powered by the power supply 464. The pinch valve 410is closed or inhibited from opening when an error state is declared.However, the perfusionist is able to depress the mechanical releasebutton 412 to push the pinch rod 458 down and open the pinch valve 410at any time during the Automatic Mode to open the pinch valve 410.

The operating system will neither automatically open the pinch valve 410nor respond to the MANUAL key depressed by the perfusionist if theoperating system is in the battery backup state. Again, the perfusionistis able to depress the mechanical release button 412 to push the pinchrod 458 down and open the pinch valve 410. When air is sensed in VARD130, the perfusionist is prompted to depress the mechanical releasebutton 412, and the pinch valve 410 will remain open as long as theperfusionist continues to depress the mechanical release button 412. Inpractice, the perfusionist is expected to observe the air being purgedthrough the distal purge line segment 147 and to release the mechanicalrelease button 412 when blood is observed in purge line 141 or purgeline segment 147.

In addition, there are distinct AAR responses in the Automatic Mode todetection of air between the upper pair of piezoelectric elements 138A,138B and the lower pair of piezoelectric elements 138C, 138D. Airdetected between the lower pair of piezoelectric elements 138C, 138Dindicates that too much air is entering the extracorporeal blood circuit100 possibly from an air leak in the table lines or the cannulaeextending into the venous and arterial vasculature of the patient. Theerror message “AIR IN VARD” of FIG. 48 is displayed by the LCD screen430 if air is detected between the lower pair of piezoelectric elements138C, 138D. The red Alarm LED flashes accompanied with the audible Alarmtone emitted by audible tone generator 416.

The operating power state is determined in step S160 of FIG. 17A, andthe message of FIG. 57 is displayed in step S162 when the operatingsystem is relying on the backup battery 462. The yellow Caution LEDflashes accompanied with a single repeating, audible Caution toneemitted by audible tone generator 416. Thus, the message of FIG. 27 thatwould be typically displayed in the absence of air detected in the VARD130 is not displayed on the LCD screen 430 if the operating system isrelying on the backup battery 462.

The message of FIG. 29 is displayed in step S168 when air is onlydetected between the upper piezoelectric elements 138A, 138B, asdetermined in steps S164 and S166. Again, the yellow Caution LED flashesaccompanied with a single repeating, audible Caution tone emitted byaudible tone generator 416. The perfusionist manually opens the pinchvalve 410 in step S170 by depressing the mechanical release button 412until the air is no longer detected between the upper piezoelectricelements 138A, 138B. The message of FIG. 57 is then displayed again onthe LCD screen 430 in step S162 because the operating system continuesto be powered by the backup battery 462.

The message shown in FIG. 49 is displayed and the Alarm sound and redlight are emitted in step S172 if air is detected between the lowerpiezoelectric elements 138C, 138D and between the upper piezoelectricelements 138A, 138B. The perfusionist manually opens the pinch valve 410in step S174 by depressing the mechanical release button 412 until theair is no longer detected between the lower piezoelectric elements 138C,138D. The perfusionist also takes appropriate corrective actions in stepS178 to locate and stem air suction into the extracorporeal bloodcircuit 100 or in the table lines and cannulae and may also slow thespeed of the blood pump 150.

The message of FIG. 29 is then displayed in step S168 when air is onlydetected between the upper piezoelectric elements 138A, 138B, asdetermined in steps S164 and S166. Again, the yellow Caution LED flashesaccompanied with a single repeating, audible Caution tone emitted byaudible tone generator 416. The perfusionist continues to manually openthe pinch valve 410 in step S174 by depressing the mechanical releasebutton 412 until the air is no longer detected between the lowerpiezoelectric elements 138C, 138D, and the message of FIG. 57 is againdisplayed on the LCD screen 430 in step S142 because the operatingsystem continues to be powered by the backup battery 462.

The automatic application of power to the solenoid to lower the pinchrod 458 to automatically open the pinch valve 410 can take place in stepS184 or step S194 when the determination is made in steps S160 that theAAR operating system is powered by the power supply 464 and no errorstates are declared in step S134 as confirmed in steps S182 and S192,respectively.

In the absence of a declared error state, the message shown in FIG. 28is displayed on the LCD screen 430 and the yellow Caution LED flashesaccompanied by a Caution tone emitted by audible tone generator 416 instep S190 if air is detected between the upper piezoelectric elements138A, 138B in step S188 and is not detected between the lowerpiezoelectric elements 138C, 138D in step S178. The pinch valve 410 isautomatically opened in step S194, and air is purged through the VARDpurge line 141 until air is no longer detected between the upperpiezoelectric elements 138A, 138B in step S188. The message shown inFIG. 27 is displayed in step S196 when air is no longer detected betweenthe upper piezoelectric elements 138A, 138B.

Similarly, in the absence of a declared error state, the message shownin FIG. 48 is displayed on the LCD screen 430 and the red Alarm LEDflashes accompanied with an Alarm sound emitted by audible tonegenerator 416 in step S180 if air is detected between the upperpiezoelectric elements 138A, 138B and the lower piezoelectric elements138C, 138D in step S178. The pinch valve 410 is automatically opened instep S184, and air is purged through the VARD purge line 141 until airis no longer detected between the lower piezoelectric elements 138C,138D in step S178. The perfusionist also takes appropriate correctiveactions in step S178 to locate and stem air suction into theextracorporeal blood circuit 100 or in the table lines and cannulae andmay also slow the speed of the blood pump 150. It should be noted thatthe speed of the blood pump 150 may be automatically lowered if air isdetected between the upper piezoelectric elements 138A, 138B and thelower piezoelectric elements 138C, 138D in step S178.

Then, air is detected between the upper piezoelectric elements 138A,138B in step S188, the message shown in FIG. 28 is displayed on the LCDscreen 430 and the yellow Caution LED flashes accompanied by a Cautiontone emitted by audible tone generator 416 in step S190. The pinch valve410 remains automatically opened in step S194, and air is purged throughthe VARD purge line 141 until air is no longer detected between theupper piezoelectric elements 138A, 138B in step S188. The message shownin FIG. 27 is displayed in step S196 when air is no longer detectedbetween the upper piezoelectric elements 138A, 138B.

In this way, air is purged automatically in step S184 or S194 as long asno error state is declared in step S134 of FIG. 16B resulting in theerror messages of FIGS. 50–56 that inhibit opening of the pinch valve asdetermined in steps S182 and S192, respectively. If an error state isdeclared in step S134, the perfusionist may choose to manually open thepinch valve 410 by depressing the mechanical release button 412 or theMANUAL key in step S186. Other appropriate corrective action is to betaken in accordance with steps S146 and S148 of FIG. 16B. Thus, the AARsystem of the present invention can be employed in manual and automaticoperating modes to reliably detect air in the VARD 130 and remove it.

The various sensors and error condition monitors of the AAR operatingsystem function independently and in parallel operations. It will beunderstood that the steps of the operating algorithm performed by theAAR operating system depicted in FIGS. 16A–16B and 17A–17B are merelyexemplary and that they can be performed in somewhat different order.

CONCLUSION

All patents and publications referenced herein are hereby incorporatedby reference in their entireties.

It will be understood that certain of the above-described structures,functions and operations of the above-described preferred embodimentsare not necessary to practice the present invention and are included inthe description simply for completeness of an exemplary embodiment orembodiments. It will also be understood that there may be otherstructures, functions and operations ancillary to the typicalperformance of a cardiac bypass procedure that are not disclosed and arenot necessary to the practice of the present invention.

In addition, it will be understood that specifically describedstructures, functions and operations set forth in the above-referencedpatents can be practiced in conjunction with the present invention, butthey are not essential to its practice.

It is therefore to be understood, that within the scope of the appendedclaims, the invention may be practiced otherwise than as specificallydescribed without actually departing from the spirit and scope of thepresent invention.

1. A method of operating an active air removal (AAR) system to purge airfrom an integrated extracorporeal blood circuit providing extracorporealoxygenation of a patient's blood during cardiopulmonary bypass surgeryadapted to be performed in the presence of a perfusionist on a patientin an operating room, the operating method comprising: providing an airremoval device incorporated in the extracorporeal blood circuit, the airremoval device comprising: an air removal device housing enclosing achamber; an air removal device purge port through the housing to thechamber; an air sensor supported by the air removal device housingadapted to provide an air sensor signal indicative of air in the airremoval device housing; an air removal device purge line coupled to theair removal device purge port and extending to a purge line connectoradapted to be coupled to a vacuum source to apply suction to the airremoval device purge port to draw air therefrom; providing an AARcontroller operating under the control of an AAR operating algorithm;locating a portion of the air removal purge line extending through apurge valve of the AAR controller, the purge valve movable between apurge valve open position and a purge valve closed position; couplingthe air sensor with the AAR controller; commencing the AAR controlleroperating algorithm that: enters a self-test mode that performsspecified self-tests of components and operating conditions of the AARcontroller; progresses to a standby mode when self-tests are completedto monitor specified components and operating conditions of the AARcontroller, to power the air sensor, and to monitor the air sensorsignal; and responds to a perfusionist initiated command to enter anautomatic mode from the standby mode enabling automatic movement of thepurge valve from the closed position to the open position when the airsensor signal is indicative of air in the air removal device housing toallow air sensed in the air removal device to be purged through thepurge line by the suction of the vacuum source; wherein the AARcontroller operating system is powered by a power supply adapted to becoupled to mains power or by a backup battery, and wherein a power stateself-test is performed in the self-test mode comprising: determining ifthe power supply is operative and capable of supplying operating powerto the AAR controller operating system; determining if the backupbattery is present and capable of supplying operating power to the AARcontroller operating system; supplying operating power from the backupbattery to the AAR controller operating system when the power supply isdetermined to be inoperative or incapable of supplying operating powerto the AAR controller operating system and the backup battery isdetermined to be present and capable of supplying operating power to theAAR controller operating system; and further comprising inhibiting theautomatic movement of the purge valve from the closed position to theopen position in the automatic mode when the air sensor signal isindicative of air in the air removal device housing if the power supplyis determined to be inoperative or incapable of supplying operatingpower to the AAR controller operating system.
 2. The operating method ofclaim 1, wherein the AAR controller further comprises a mechanicalrelease button interconnected with the purge valve adapted to enablemanual opening of the purge valve by the perfusionist in the standby andthe automatic modes.
 3. The operating method of claim 1, furthercomprising: determining an error state of the purging system; andalerting the perfusionist of the error state.
 4. The purging method ofclaim 3, wherein the alerting step comprises: formulating alert messagesignals related to the determined error state; and displaying alertmessages readable by the perfusionist on a display screen.
 5. Thepurging method of claim 3, wherein the alerting step comprises:formulating alert sound signals related to the determined error state;and applying the formulated alert sound signals to a sound emitter thatemits audible alert sounds that can be heard by the perfusionist.
 6. Thepurging method of claim 3, wherein the alerting step comprises:formulating alert light signals related to the determined error state;and applying the formulated alert light signals to at least one lightemitter that emits visual light in response to the alert light signalsthat can be seen by the perfusionist.
 7. A method of operating an activeair removal (AAR) system to purge air from an integrated extracorporealblood circuit providing extracorporeal oxygenation of a patient's bloodduring cardiopulmonary bypass surgery adapted to be performed in thepresence of a perfusionist on a patient in an operating room, theoperating method comprising: providing an air removal deviceincorporated in the extracorporeal blood circuit, the air removal devicecomprising: an air removal device housing enclosing a chamber; an airremoval device purge port through the housing to the chamber; an airsensor supported by the air removal device housing adapted to provide anair sensor signal indicative of air in the air removal device housing;an air removal device purge line coupled to the air removal device purgeport and extending to a purge line connector adapted to be coupled to avacuum source to apply suction to the air removal device purge port todraw air therefrom; providing an AAR controller operating under thecontrol of an AAR operating algorithm; locating a portion of the airremoval purge line extending through a purge valve of the AARcontroller, the purge valve movable between a purge valve open positionand a purge valve closed position; coupling the air sensor with the AARcontroller; commencing the AAR controller operating algorithm that:enters a self-test mode that performs specified self-tests of componentsand operating conditions of the AAR controller; progresses to a standbymode when self-tests are completed to monitor specified components andoperating conditions of the AAR controller, to power the air sensor, andto monitor the air sensor signal; and responds to a perfusionistinitiated command to enter an automatic mode from the standby modeenabling automatic movement of the purge valve from the closed positionto the open position when the air sensor signal is indicative of air inthe air removal device housing to allow air sensed in the air removaldevice to be purged through the purge line by the suction of the vacuumsource; determining an error state of the purging system; and inhibitingthe automatic movement of the purge valve from the closed position tothe open position in the automatic mode when an error state is detected;wherein the error determining step comprises determining the presence offluid in the purge line; wherein the AAR controller further comprises afluid in line (FIL) sensor arranged with respect to the purge valve, andfurther comprising: locating a further portion of the purge line throughthe FIL sensor; and powering the FIL sensor to develop a FIL sensorsignal indicative of the absence or presence of fluid in the purge line,and wherein: the error determining step comprises determining thepresence of fluid in the purge line from the FIL sensor signal; andwherein the AAR controller further comprises a mechanical release buttoninterconnected with the purge valve adapted to enable manual opening ofthe purge valve by the perfusionist.
 8. A method of operating an activeair removal (AAR) system to purge air from an integrated extracorporealblood circuit providing extracorporeal oxygenation of a patient's bloodduring cardiopulmonary bypass surgery adapted to be performed in thepresence of a perfusionist on a patient in an operating room, theoperating method comprising: providing an air removal deviceincorporated in the extracorporeal blood circuit, the air removal devicecomprising: an air removal device housing enclosing a chamber; an airremoval device purge port through the housing to the chamber; an airsensor supported by the air removal device housing adapted to provide anair sensor signal indicative of air in the air removal device housing;an air removal device purge line coupled to the air removal device purgeport and extending to a purge line connector adapted to be coupled to avacuum source to apply suction to the air removal device purge port todraw air therefrom; providing an AAR controller operating under thecontrol of an AAR operating algorithm; locating a portion of the airremoval purge line extending through a purge valve of the AARcontroller, the purge valve movable between a purge valve open positionand a purge valve closed position; coupling the air sensor with the AARcontroller; commencing the AAR controller operating algorithm that:enters a self-test mode that performs specified self-tests of componentsand operating conditions of the AAR controller; progresses to a standbymode when self-tests are completed to monitor specified components andoperating conditions of the AAR controller, to power the air sensor, andto monitor the air sensor signal; and responds to a perfusionistinitiated command to enter an automatic mode from the standby modeenabling automatic movement of the purge valve from the closed positionto the open position when the air sensor signal is indicative of air inthe air removal device housing to allow air sensed in the air removaldevice to be purged through the purge line by the suction of the vacuumsource; wherein the error determining step comprises determining anerror state of the air sensor; and further comprising: connecting an airsensor cable between the AAR controller and the air sensor; and whereinthe error determining step determines if electrical continuity ispresent in the connection of the air sensor cable between the AARcontroller and the air sensor.
 9. A method of operating an active airremoval (AAR) system to purge air from an integrated extracorporealblood circuit providing extracorporeal oxygenation of a patient's bloodduring cardiopulmonary bypass surgery adapted to be performed in thepresence of a perfusionist on a patient in an operating room, theoperating method comprising: providing an air removal deviceincorporated in the extracorporeal blood circuit, the air removal devicecomprising: an air removal device housing enclosing a chamber; an airremoval device purge port through the housing to the chamber; an airsensor supported by the air removal device housing adapted to provide anair sensor signal indicative of air in the air removal device housing;an air removal device purge line coupled to the air removal device purgeport and extending to a purge line connector adapted to be coupled to avacuum source to apply suction to the air removal device purge port todraw air therefrom; providing an AAR controller operating under thecontrol of an AAR operating algorithm; locating a portion of the airremoval purge line extending through a purge valve of the AARcontroller, the purge valve movable between a purge valve open positionand a purge valve closed position; coupling the air sensor with the AARcontroller; commencing the AAR controller operating algorithm that:enters a self-test mode that performs specified self-tests of componentsand operating conditions of the AAR controller; progresses to a standbymode when self-tests are completed to monitor specified components andoperating conditions of the AAR controller, to power the air sensor, andto monitor the air sensor signal; and responds to a perfusionistinitiated command to enter an automatic mode from the standby modeenabling automatic movement of the purge valve from the closed positionto the open position when the air sensor signal is indicative of air inthe air removal device housing to allow air sensed in the air removaldevice to be purged through the purge line by the suction of the vacuumsource; determining an error state of the purging system; inhibiting theautomatic movement of the purge valve from the closed position to theopen position in the automatic mode when an error state is detected; andwherein the error determining step comprises determining a low vacuumcondition.
 10. The operating method of claim 9, wherein: the AARcontroller further comprises a vacuum sensor arranged with respect tothe purge line to provide a vacuum signal indicative of vacuum in thepurge line; the error determining step determines a low vacuum errorstate if the sensed vacuum falls below a minimum vacuum.
 11. A method ofoperating an active air removal (AAR) system to purge air from anintegrated extracorporeal blood circuit providing extracorporealoxygenation of a patient's blood during cardiopulmonary bypass surgeryadapted to be performed in the presence of a perfusionist on a patientin an operating room, the operating method comprising: providing an airremoval device incorporated in the extracorporeal blood circuit, the airremoval device comprising: an air removal device housing enclosing achamber; an air removal device purge port through the housing to thechamber; an air sensor supported by the air removal device housingadapted to provide an air sensor signal indicative of air in the airremoval device housing; an air removal device purge line coupled to theair removal device purge port and extending to a purge line connectoradapted to be coupled to a vacuum source to apply suction to the airremoval device purge port to draw air therefrom; providing an AARcontroller operating under the control of an AAR operating algorithm;locating a portion of the air removal purge line extending through apurge valve of the AAR controller, the purge valve movable between apurge valve open position and a purge valve closed position; couplingthe air sensor with the AAR controller; commencing the AAR controlleroperating algorithm that: enters a self-test mode that performsspecified self-tests of components and operating conditions of the AARcontroller; progresses to a standby mode when self-tests are completedto monitor specified components and operating conditions of the AARcontroller, to power the air sensor, and to monitor the air sensorsignal; and responds to a perfusionist initiated command to enter anautomatic mode from the standby mode enabling automatic movement of thepurge valve from the closed position to the open position when the airsensor signal is indicative of air in the air removal device housing toallow air sensed in the air removal device to be purged through thepurge line by the suction of the vacuum source; determining an errorstate of the purging system; inhibiting the automatic movement of thepurge valve from the closed position to the open position in theautomatic mode when an error state is detected; and wherein the errordetermining step comprises determining a purge valve error state of thepurge valve.
 12. The operating method of claim 11, wherein the purgevalve error state determining step comprises: commanding the purge valveto move into one of the purge valve open and closed positions; sensingthe purge valve position and providing a purge valve position signalindicative of the actual position of the purge valve; and determining aposition error state of the purge valve or the purge valve operatingmeans when the sensed purge valve position signal does not confirm thatthe purge valve is in the commanded purge valve open position or purgevalve closed position.
 13. The operating method of claim 11, wherein:the purge valve comprises a pinch valve having a valve slot receivingthe portion of the purge line and a pinch rod adapted to be movedbetween a purge valve closed position extending into the slot tocompress the purge line and a purge valve open position retracted out ofthe slot; and the purge valve opening step comprises moving the pinchrod from the purge valve closed position to the purge valve openposition.
 14. The operating method of claim 13, further comprising:determining a pinch valve error state of the pinch valve; and inhibitingthe automatic movement of the pinch valve from the closed position tothe open position in the automatic mode when a pinch valve error stateis detected.
 15. The operating method of claim 14, wherein the pinchvalve error state determining step comprises: commanding the pinch rodto move into one of the purge valve open and closed positions; sensingthe pinch rod position and providing a pinch rod position signalindicative of the actual position of the pinch rod; and determining aposition error state of the pinch valve when the pinch rod positionsignal does not confirm that the pinch rod is in the commanded purgevalve open or purge valve closed position.
 16. A method of operating anactive air removal (AAR) system to purge air from an integratedextracorporeal blood circuit providing extracorporeal oxygenation of apatient's blood during cardiopulmonary bypass surgery adapted to beperformed in the presence of a perfusionist on a patient in an operatingroom, the operating method comprising: providing an air removal deviceincorporated in the extracorporeal blood circuit, the air removal devicecomprising: an air removal device housing enclosing a chamber; an airremoval device purge port through the housing to the chamber; an airsensor supported by the air removal device housing adapted to provide anair sensor signal indicative of air in the air removal device housing;an air removal device purge line coupled to the air removal device purgeport and extending to a purge line connector adapted to be coupled to avacuum source to apply suction to the air removal device purge port todraw air therefrom; providing an AAR controller operating under thecontrol of an AAR operating algorithm; locating a portion of the airremoval purge line extending through a purge valve of the AARcontroller, the purge valve movable between a purge valve open positionand a purge valve closed position; coupling the air sensor with the AARcontroller; commencing the AAR controller operating algorithm that:enters a self-test mode that performs specified self-tests of componentsand operating conditions of the AAR controller; progresses to a standbymode when self-tests are completed to monitor specified components andoperating conditions of the AAR controller, to power the air sensor, andto monitor the air sensor signal; and responds to a perfusionistinitiated command to enter an automatic mode from the standby modeenabling automatic movement of the purge valve from the closed positionto the open position when the air sensor signal is indicative of air inthe air removal device housing to allow air sensed in the air removaldevice to be purged through the purge line by the suction of the vacuumsource; wherein: the AAR controller further comprises a vacuum sensorarranged with respect to the purge line to provide a vacuum signalindicative of vacuum in the purge line when the purge valve is closed;and determining if the sensed vacuum exceeds a minimum vacuum; andissuing an alert if the sensed vacuum does not exceed the minimumvacuum.